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Smith-Lemli-Opitz syndrome(SLOS)

MedGen UID:
61231
Concept ID:
C0175694
Disease or Syndrome
Synonyms: 7-Dehydrocholesterol reductase deficiency; LETHAL ACRODYSGENITAL SYNDROME; POLYDACTYLY, SEX REVERSAL, RENAL HYPOPLASIA, AND UNILOBAR LUNG; RSH syndrome; RUTLEDGE LETHAL MULTIPLE CONGENITAL ANOMALY SYNDROME; SLO syndrome type 1; SLOS; Smith-Lemli-Opitz syndrome type 1
SNOMED CT: 7-Dehydrocholesterol reductase deficiency (43929004); Smith-Lemli-Opitz syndrome (43929004)
Modes of inheritance:
Autosomal recessive inheritance
MedGen UID:
141025
Concept ID:
C0441748
Intellectual Product
Source: Orphanet
A mode of inheritance that is observed for traits related to a gene encoded on one of the autosomes (i.e., the human chromosomes 1-22) in which a trait manifests in individuals with two pathogenic alleles, either homozygotes (two copies of the same mutant allele) or compound heterozygotes (whereby each copy of a gene has a distinct mutant allele).
 
Gene (location): DHCR7 (11q13.4)
 
Monarch Initiative: MONDO:0010035
OMIM®: 270400
Orphanet: ORPHA818

Disease characteristics

Excerpted from the GeneReview: Smith-Lemli-Opitz Syndrome
Smith-Lemli-Opitz syndrome (SLOS) is a congenital multiple-anomaly / cognitive impairment syndrome caused by an abnormality in cholesterol metabolism resulting from deficiency of the enzyme 7-dehydrocholesterol (7-DHC) reductase. It is characterized by prenatal and postnatal growth restriction, microcephaly, moderate-to-severe intellectual disability, and multiple major and minor malformations. The malformations include distinctive facial features, cleft palate, cardiac defects, underdeveloped external genitalia in males, postaxial polydactyly, and 2-3 syndactyly of the toes. The clinical spectrum is wide; individuals with normal development and only minor malformations have been described. [from GeneReviews]
Authors:
Malgorzata JM Nowaczyk  |  Christopher A Wassif   view full author information

Additional descriptions

From OMIM
Smith-Lemli-Opitz syndrome is an autosomal recessive multiple congenital malformation and mental retardation syndrome. Although historically a clinical distinction was often made between a classic 'type I' disorder and a more severe 'type II' disorder, in reality the syndrome constitutes a clinical and biochemical continuum from mild to severe (Opitz et al., 1987; Cunniff et al., 1997; Kelley, 1998). The discovery of the deficiency of 7-dehydrocholesterol reductase as a causative factor of the SLO syndrome (Tint et al., 1994) made this syndrome the first true metabolic syndrome of multiple congenital malformations. A multidisciplinary National Institute of Child Health and Human Development (NICHD) conference of the SLO syndrome reviewed different implications of this discovery and proposed further studies in this field. A detailed report on this conference and abstracts of presentations were provided by Opitz and de la Cruz (1994). Observations presented at an NICHD RSH/SLOS conference in September 1995 were reviewed by Kelley (1997). Kelley (1998) referred to SLOS as a metabolic malformation syndrome, but suggested that this may be an exception. Most mutations that had been related to multiple congenital malformation syndromes, i.e., disturbances of the body plan, have not been disorders of intermediary metabolism but, instead, mutations of homeobox genes and other transcriptional regulators and signaling systems. Opitz et al. (1987) gave a presumedly complete bibliography of the SLO syndrome, which was updated by Opitz et al. (1994) and included almost 200 references. They concluded that lumping SLO syndrome with the Pallister-Hall hamartoblastoma syndrome (PHS; 146510) is not justified. In a given severe case, differentiation from the Meckel syndrome (249000) may be a challenge. Herman (2003) reviewed the cholesterol biosynthetic pathway and the 6 disorders involving enzyme defects in post-squalene cholesterol biosynthesis: SLOS, desmosterolosis (602398), X-linked dominant chondrodysplasia punctata (CDPX2; 302960), CHILD syndrome (308050), lathosterolosis (607330), and hydrops-ectopic calcification-moth-eaten skeletal dysplasia (HEM; 215140).  http://www.omim.org/entry/270400
From MedlinePlus Genetics
Smith-Lemli-Opitz syndrome is a developmental disorder that affects many parts of the body. This condition is characterized by distinctive facial features, small head size (microcephaly), intellectual disability or learning problems, and behavioral problems. Many affected children have the characteristic features of autism, a developmental condition that affects communication and social interaction. Malformations of the heart, lungs, kidneys, gastrointestinal tract, and genitalia are also common. Infants with Smith-Lemli-Opitz syndrome have weak muscle tone (hypotonia), experience feeding difficulties, and tend to grow more slowly than other infants. Most affected individuals have fused second and third toes (syndactyly), and some have extra fingers or toes (polydactyly).

The signs and symptoms of Smith-Lemli-Opitz syndrome vary widely. Mildly affected individuals may have only minor physical abnormalities with learning and behavioral problems. Severe cases can be life-threatening and involve profound intellectual disability and major physical abnormalities.  https://medlineplus.gov/genetics/condition/smith-lemli-opitz-syndrome

Clinical features

From HPO
Facial capillary hemangioma
MedGen UID:
347662
Concept ID:
C1858545
Finding
Hemangioma, a benign tumor of the vascular endothelial cells with small endothelial spaces, occurring in the face.
Cryptorchidism
MedGen UID:
8192
Concept ID:
C0010417
Congenital Abnormality
Cryptorchidism, or failure of testicular descent, is a common human congenital abnormality with a multifactorial etiology that likely reflects the involvement of endocrine, environmental, and hereditary factors. Cryptorchidism can result in infertility and increases risk for testicular tumors. Testicular descent from abdomen to scrotum occurs in 2 distinct phases: the transabdominal phase and the inguinoscrotal phase (summary by Gorlov et al., 2002).
Hydronephrosis
MedGen UID:
42531
Concept ID:
C0020295
Disease or Syndrome
Severe distention of the kidney with dilation of the renal pelvis and calices.
Unilateral renal agenesis
MedGen UID:
75607
Concept ID:
C0266294
Congenital Abnormality
A unilateral form of agenesis of the kidney.
Renal hypoplasia
MedGen UID:
120571
Concept ID:
C0266295
Congenital Abnormality
Hypoplasia of the kidney.
Ambiguous genitalia
MedGen UID:
78596
Concept ID:
C0266362
Congenital Abnormality
A genital phenotype that is not clearly assignable to a single gender. Ambiguous genitalia can be evaluated using the Prader scale
Bicornuate uterus
MedGen UID:
78599
Concept ID:
C0266387
Congenital Abnormality
The presence of a bicornuate uterus.
Septate vagina
MedGen UID:
82741
Concept ID:
C0266411
Congenital Abnormality
The presence of a vaginal septum, thereby creating a vaginal duplication. The septum is longitudinal in the majority of cases.
Bifid scrotum
MedGen UID:
90968
Concept ID:
C0341787
Congenital Abnormality
Midline indentation or cleft of the scrotum.
Penoscrotal hypospadias
MedGen UID:
105291
Concept ID:
C0452147
Congenital Abnormality
A severe form of hypospadias in which the urethral opening is located at the junction of the penis and scrotum.
Small scrotum
MedGen UID:
141577
Concept ID:
C0455792
Finding
Apparently small scrotum for age.
Ureteropelvic junction obstruction
MedGen UID:
105482
Concept ID:
C0521619
Anatomical Abnormality
Blockage of urine flow from the renal pelvis to the proximal ureter.
Renal agenesis
MedGen UID:
154237
Concept ID:
C0542519
Congenital Abnormality
Agenesis, that is, failure of the kidney to develop during embryogenesis and development.
Hypospadias
MedGen UID:
163083
Concept ID:
C0848558
Congenital Abnormality
Abnormal position of urethral meatus on the ventral penile shaft (underside) characterized by displacement of the urethral meatus from the tip of the glans penis to the ventral surface of the penis, scrotum, or perineum.
Duplicated collecting system
MedGen UID:
346936
Concept ID:
C1858565
Anatomical Abnormality
A duplication of the collecting system of the kidney, defined as a kidney with two (instead of, normally, one) pyelocaliceal systems. The pyelocaliceal system is comprised of the renal pelvis and calices. The duplicated renal collecting system can be associated with a single ureter or with double ureters. In the latter case, the two ureters empty separately into the bladder or fuse to form a single ureteral orifice.
Renal cyst
MedGen UID:
854361
Concept ID:
C3887499
Disease or Syndrome
A fluid filled sac in the kidney.
Micropenis
MedGen UID:
1633603
Concept ID:
C4551492
Congenital Abnormality
Abnormally small penis. At birth, the normal penis is about 3 cm (stretched length from pubic tubercle to tip of penis) with micropenis less than 2.0-2.5 cm.
Micromelia
MedGen UID:
10031
Concept ID:
C0025995
Congenital Abnormality
The presence of abnormally small extremities.
Talipes calcaneovalgus
MedGen UID:
56270
Concept ID:
C0152237
Anatomical Abnormality
Talipes calcaneovalgus is a flexible foot deformity (as opposed to a rigid congenital vertical talus foot deformity) that can either present as a positional or structural foot deformity depending on severity and/or causality. The axis of calcaneovalgus deformity is in the tibiotalar joint, where the foot is positioned in extreme hyperextension. On inspection, the foot has an "up and out" appearance, with the dorsal forefoot practically touching the anterior aspect of the ankle and lower leg.
Short thumb
MedGen UID:
98469
Concept ID:
C0431890
Congenital Abnormality
Hypoplasia (congenital reduction in size) of the thumb.
Postaxial hand polydactyly
MedGen UID:
609221
Concept ID:
C0431904
Congenital Abnormality
Supernumerary digits located at the ulnar side of the hand (that is, on the side with the fifth finger).
2-3 toe cutaneous syndactyly
MedGen UID:
98470
Concept ID:
C0432040
Congenital Abnormality
Hip subluxation
MedGen UID:
140946
Concept ID:
C0434785
Injury or Poisoning
A partial dislocation of the hip joint, whereby the head of the femur is partially displaced from the socket.
Overlapping toe
MedGen UID:
182531
Concept ID:
C0920299
Anatomical Abnormality
Describes a foot digit resting on the dorsal surface of an adjacent digit when the foot is at rest. Initially clawing may be dynamic and only noticeable on walking. Over time the plantar plate tears, subluxation occurs at the metatarsophalangeal joint (MTPJ), and the deformity becomes permanent.
Hammertoe
MedGen UID:
209712
Concept ID:
C1136179
Anatomical Abnormality
Hyperextension of the metatarsal-phalangeal joint with hyperflexion of the proximal interphalangeal (PIP) joint.
Short toe
MedGen UID:
322858
Concept ID:
C1836195
Finding
A toe that appears disproportionately short compared to the foot.
Proximal placement of thumb
MedGen UID:
356033
Concept ID:
C1865572
Finding
Proximal mislocalization of the thumb.
Postaxial foot polydactyly
MedGen UID:
384489
Concept ID:
C2112129
Finding
Polydactyly of the foot most commonly refers to the presence of six toes on one foot. Postaxial polydactyly affects the lateral ray and the duplication may range from a well-formed articulated digit to a rudimentary digit.
Metatarsus adductus
MedGen UID:
898667
Concept ID:
C4082169
Anatomical Abnormality
The metatarsals are deviated medially (tibially), that is, the bones in the front half of the foot bend or turn in toward the body.
2-3 toe syndactyly
MedGen UID:
1645640
Concept ID:
C4551570
Congenital Abnormality
Syndactyly with fusion of toes two and three.
Coarctation of aorta
MedGen UID:
1617
Concept ID:
C0003492
Congenital Abnormality
Coarctation of the aorta is a narrowing or constriction of a segment of the aorta.
Hypertrophic cardiomyopathy
MedGen UID:
2881
Concept ID:
C0007194
Disease or Syndrome
Hypertrophic cardiomyopathy (HCM) is defined by the presence of increased ventricular wall thickness or mass in the absence of loading conditions (hypertension, valve disease) sufficient to cause the observed abnormality.
Patent ductus arteriosus
MedGen UID:
4415
Concept ID:
C0013274
Congenital Abnormality
In utero, the ductus arteriosus (DA) serves to divert ventricular output away from the lungs and toward the placenta by connecting the main pulmonary artery to the descending aorta. A patent ductus arteriosus (PDA) in the first 3 days of life is a physiologic shunt in healthy term and preterm newborn infants, and normally is substantially closed within about 24 hours after bith and completely closed after about three weeks. Failure of physiologcal closure is referred to a persistent or patent ductus arteriosus (PDA). Depending on the degree of left-to-right shunting, PDA can have clinical consequences.
Atrial septal defect
MedGen UID:
6753
Concept ID:
C0018817
Congenital Abnormality
Atrial septal defect (ASD) is a congenital abnormality of the interatrial septum that enables blood flow between the left and right atria via the interatrial septum.
Ventricular septal defect
MedGen UID:
42366
Concept ID:
C0018818
Congenital Abnormality
A hole between the two bottom chambers (ventricles) of the heart. The defect is centered around the most superior aspect of the ventricular septum.
Hypertensive disorder
MedGen UID:
6969
Concept ID:
C0020538
Disease or Syndrome
The presence of chronic increased pressure in the systemic arterial system.
Ventricular fibrillation
MedGen UID:
21844
Concept ID:
C0042510
Disease or Syndrome
Uncontrolled contractions of muscles fibers in the left ventricle not producing contraction of the left ventricle. Ventricular fibrillation usually begins with a ventricular premature contraction and a short run of rapid ventricular tachycardia degenerating into uncoordinating ventricular fibrillations.
Fetal growth restriction
MedGen UID:
4693
Concept ID:
C0015934
Pathologic Function
An abnormal restriction of fetal growth with fetal weight below the tenth percentile for gestational age.
Short stature
MedGen UID:
87607
Concept ID:
C0349588
Finding
A height below that which is expected according to age and gender norms. Although there is no universally accepted definition of short stature, many refer to "short stature" as height more than 2 standard deviations below the mean for age and gender (or below the 3rd percentile for age and gender dependent norms).
Growth delay
MedGen UID:
99124
Concept ID:
C0456070
Pathologic Function
A deficiency or slowing down of growth pre- and postnatally.
Failure to thrive
MedGen UID:
746019
Concept ID:
C2315100
Disease or Syndrome
Failure to thrive (FTT) refers to a child whose physical growth is substantially below the norm.
Abdominal distention
MedGen UID:
34
Concept ID:
C0000731
Finding
Distention of the abdomen.
Constipation
MedGen UID:
1101
Concept ID:
C0009806
Sign or Symptom
Infrequent or difficult evacuation of feces.
Hepatomegaly
MedGen UID:
42428
Concept ID:
C0019209
Finding
Abnormally increased size of the liver.
Cirrhosis of liver
MedGen UID:
7368
Concept ID:
C0023890
Disease or Syndrome
A chronic disorder of the liver in which liver tissue becomes scarred and is partially replaced by regenerative nodules and fibrotic tissue resulting in loss of liver function.
Vomiting
MedGen UID:
12124
Concept ID:
C0042963
Sign or Symptom
Forceful ejection of the contents of the stomach through the mouth by means of a series of involuntary spasmic contractions.
Intestinal malrotation
MedGen UID:
113153
Concept ID:
C0221210
Congenital Abnormality
An abnormality of the intestinal rotation and fixation that normally occurs during the development of the gut. This can lead to volvulus, or twisting of the intestine that causes obstruction and necrosis.
Feeding difficulties
MedGen UID:
65429
Concept ID:
C0232466
Finding
Impaired ability to eat related to problems gathering food and getting ready to suck, chew, or swallow it.
Congenital hypertrophic pyloric stenosis
MedGen UID:
196010
Concept ID:
C0700639
Congenital Abnormality
Pyloric stenosis, also known as infantile hypertrophic pyloric stenosis, is an uncommon condition in infants characterized by abnormal thickening of the pylorus muscles in the stomach leading to gastric outlet obstruction. Clinically infants are well at birth. Then, at 3 to 6 weeks of age, the infants present with projectile vomiting, potentially leading to dehydration and weight loss.
Cholestatic liver disease
MedGen UID:
163651
Concept ID:
C0860204
Disease or Syndrome
Gastrointestinal dysmotility
MedGen UID:
324638
Concept ID:
C1836923
Finding
Abnormal intestinal contractions, such as spasms and intestinal paralysis, related to the loss of the ability of the gut to coordinate muscular activity because of endogenous or exogenous causes.
Poor suck
MedGen UID:
324693
Concept ID:
C1837142
Finding
An inadequate sucking reflex, resulting in the difficult of newborns to be breast-fed.
Hepatic steatosis
MedGen UID:
398225
Concept ID:
C2711227
Disease or Syndrome
Steatosis is a term used to denote lipid accumulation within hepatocytes.
Gastroesophageal reflux
MedGen UID:
1368658
Concept ID:
C4317146
Finding
A condition in which the stomach contents leak backwards from the stomach into the esophagus through the lower esophageal sphincter.
Low-set ears
MedGen UID:
65980
Concept ID:
C0239234
Congenital Abnormality
Upper insertion of the ear to the scalp below an imaginary horizontal line drawn between the inner canthi of the eye and extending posteriorly to the ear.
Posteriorly rotated ears
MedGen UID:
96566
Concept ID:
C0431478
Congenital Abnormality
A type of abnormal location of the ears in which the position of the ears is characterized by posterior rotation (the superior part of the ears is rotated towards the back of the head, and the inferior part of the ears towards the front).
Hearing impairment
MedGen UID:
235586
Concept ID:
C1384666
Disease or Syndrome
A decreased magnitude of the sensory perception of sound.
Aggressive behavior
MedGen UID:
1375
Concept ID:
C0001807
Individual Behavior
Behavior or an act aimed at harming a person, animal, or physical property (e.g., acts of physical violence; shouting, swearing, and using harsh language; slashing someone's tires).
Autism
MedGen UID:
13966
Concept ID:
C0004352
Mental or Behavioral Dysfunction
Autism, the prototypic pervasive developmental disorder (PDD), is usually apparent by 3 years of age. It is characterized by a triad of limited or absent verbal communication, a lack of reciprocal social interaction or responsiveness, and restricted, stereotypic, and ritualized patterns of interests and behavior (Bailey et al., 1996; Risch et al., 1999). 'Autism spectrum disorder,' sometimes referred to as ASD, is a broader phenotype encompassing the less severe disorders Asperger syndrome (see ASPG1; 608638) and pervasive developmental disorder, not otherwise specified (PDD-NOS). 'Broad autism phenotype' includes individuals with some symptoms of autism, but who do not meet the full criteria for autism or other disorders. Mental retardation coexists in approximately two-thirds of individuals with ASD, except for Asperger syndrome, in which mental retardation is conspicuously absent (Jones et al., 2008). Genetic studies in autism often include family members with these less stringent diagnoses (Schellenberg et al., 2006). Levy et al. (2009) provided a general review of autism and autism spectrum disorder, including epidemiology, characteristics of the disorder, diagnosis, neurobiologic hypotheses for the etiology, genetics, and treatment options. Genetic Heterogeneity of Autism Autism is considered to be a complex multifactorial disorder involving many genes. Accordingly, several loci have been identified, some or all of which may contribute to the phenotype. Included in this entry is AUTS1, which has been mapped to chromosome 7q22. Other susceptibility loci include AUTS3 (608049), which maps to chromosome 13q14; AUTS4 (608636), which maps to chromosome 15q11; AUTS6 (609378), which maps to chromosome 17q11; AUTS7 (610676), which maps to chromosome 17q21; AUTS8 (607373), which maps to chromosome 3q25-q27; AUTS9 (611015), which maps to chromosome 7q31; AUTS10 (611016), which maps to chromosome 7q36; AUTS11 (610836), which maps to chromosome 1q41; AUTS12 (610838), which maps to chromosome 21p13-q11; AUTS13 (610908), which maps to chromosome 12q14; AUTS14A (611913), which has been found in patients with a deletion of a region of 16p11.2; AUTS14B (614671), which has been found in patients with a duplication of a region of 16p11.2; AUTS15 (612100), associated with mutation in the CNTNAP2 gene (604569) on chromosome 7q35-q36; AUTS16 (613410), associated with mutation in the SLC9A9 gene (608396) on chromosome 3q24; AUTS17 (613436), associated with mutation in the SHANK2 gene (603290) on chromosome 11q13; AUTS18 (615032), associated with mutation in the CHD8 gene (610528) on chromosome 14q11; AUTS19 (615091), associated with mutation in the EIF4E gene (133440) on chromosome 4q23; and AUTS20 (618830), associated with mutation in the NLGN1 gene (600568) on chromosome 3q26. (NOTE: the symbol 'AUTS2' has been used to refer to a gene on chromosome 7q11 (KIAA0442; 607270) and therefore is not used as a part of this autism locus series.) There are several X-linked forms of autism susceptibility: AUTSX1 (300425), associated with mutations in the NLGN3 gene (300336); AUTSX2 (300495), associated with mutations in NLGN4 (300427); AUTSX3 (300496), associated with mutations in MECP2 (300005); AUTSX4 (300830), associated with variation in the region on chromosome Xp22.11 containing the PTCHD1 gene (300828); AUTSX5 (300847), associated with mutations in the RPL10 gene (312173); and AUTSX6 (300872), associated with mutation in the TMLHE gene (300777). A locus on chromosome 2q (606053) associated with a phenotype including intellectual disability and speech deficits was formerly designated AUTS5. Folstein and Rosen-Sheidley (2001) reviewed the genetics of autism.
Aganglionic megacolon
MedGen UID:
5559
Concept ID:
C0019569
Disease or Syndrome
The disorder described by Hirschsprung (1888) and known as Hirschsprung disease or aganglionic megacolon is characterized by congenital absence of intrinsic ganglion cells in the myenteric (Auerbach) and submucosal (Meissner) plexuses of the gastrointestinal tract. Patients are diagnosed with the short-segment form (S-HSCR, approximately 80% of cases) when the aganglionic segment does not extend beyond the upper sigmoid, and with the long-segment form (L-HSCR) when aganglionosis extends proximal to the sigmoid (Amiel et al., 2008). Total colonic aganglionosis and total intestinal HSCR also occur. Genetic Heterogeneity of Hirschsprung Disease Several additional loci for isolated Hirschsprung disease have been mapped. HSCR2 (600155) is associated with variation in the EDNRB gene (131244) on 13q22; HSCR3 (613711) is associated with variation in the GDNF gene (600837) on 5p13; HSCR4 (613712) is associated with variation in the EDN3 gene (131242) on 20q13; HSCR5 (600156) maps to 9q31; HSCR6 (606874) maps to 3p21; HSCR7 (606875) maps to 19q12; HSCR8 (608462) maps to 16q23; and HSCR9 (611644) maps to 4q31-q32. HSCR also occurs as a feature of several syndromes including the Waardenburg-Shah syndrome (277580), Mowat-Wilson syndrome (235730), Goldberg-Shprintzen syndrome (609460), and congenital central hypoventilation syndrome (CCHS; 209880). Whereas mendelian modes of inheritance have been described for syndromic HSCR, isolated HSCR stands as a model for genetic disorders with complex patterns of inheritance. Isolated HSCR appears to be of complex nonmendelian inheritance with low sex-dependent penetrance and variable expression according to the length of the aganglionic segment, suggestive of the involvement of one or more genes with low penetrance. The development of surgical procedures decreased mortality and morbidity, which allowed the emergence of familial cases. HSCR occurs as an isolated trait in 70% of patients, is associated with chromosomal anomaly in 12% of cases, and occurs with additional congenital anomalies in 18% of cases (summary by Amiel et al., 2008).
Hydrocephalus
MedGen UID:
9335
Concept ID:
C0020255
Disease or Syndrome
Hydrocephalus is an active distension of the ventricular system of the brain resulting from inadequate passage of CSF from its point of production within the cerebral ventricles to its point of absorption into the systemic circulation.
Seizure
MedGen UID:
20693
Concept ID:
C0036572
Sign or Symptom
A seizure is an intermittent abnormality of nervous system physiology characterized by a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain.
Self-mutilation
MedGen UID:
19925
Concept ID:
C0036601
Injury or Poisoning
Deliberate harm to one's body resulting in tissue damage, without a conscious intent to die.
Arachnoid cyst
MedGen UID:
86860
Concept ID:
C0078981
Disease or Syndrome
An extra-parenchymal and intra-arachnoidal collection of fluid with a composition similar to that of cerebrospinal fluid.
Holoprosencephaly sequence
MedGen UID:
38214
Concept ID:
C0079541
Congenital Abnormality
Nonsyndromic holoprosencephaly is an abnormality of brain development that also affects the head and face. Normally, the brain divides into two halves (hemispheres) during early development. Holoprosencephaly occurs when the brain fails to divide properly into the right and left hemispheres. This condition is called nonsyndromic to distinguish it from other types of holoprosencephaly caused by genetic syndromes, chromosome abnormalities, or substances that cause birth defects (teratogens). The severity of nonsyndromic holoprosencephaly varies widely among affected individuals, even within the same family.\n\nNonsyndromic holoprosencephaly can be grouped into four types according to the degree of brain division. From most to least severe, the types are known as alobar, semi-lobar, lobar, and middle interhemispheric variant (MIHV). In the most severe forms of nonsyndromic holoprosencephaly, the brain does not divide at all. These affected individuals have one central eye (cyclopia) and a tubular nasal structure (proboscis) located above the eye. Most babies with severe nonsyndromic holoprosencephaly die before birth or soon after. In the less severe forms, the brain is partially divided and the eyes are usually set close together (hypotelorism). The life expectancy of these affected individuals varies depending on the severity of symptoms.\n\nPeople with nonsyndromic holoprosencephaly often have a small head (microcephaly), although they can develop a buildup of fluid in the brain (hydrocephalus) that causes increased head size (macrocephaly). Other features may include an opening in the roof of the mouth (cleft palate) with or without a split in the upper lip (cleft lip), one central front tooth instead of two (a single maxillary central incisor), and a flat nasal bridge. The eyeballs may be abnormally small (microphthalmia) or absent (anophthalmia).\n\nSome individuals with nonsyndromic holoprosencephaly have a distinctive pattern of facial features, including a narrowing of the head at the temples, outside corners of the eyes that point upward (upslanting palpebral fissures), large ears, a short nose with upturned nostrils, and a broad and deep space between the nose and mouth (philtrum). In general, the severity of facial features is directly related to the severity of the brain abnormalities. However, individuals with mildly affected facial features can have severe brain abnormalities. Some people do not have apparent structural brain abnormalities but have some of the facial features associated with this condition. These individuals are considered to have a form of the disorder known as microform holoprosencephaly and are typically identified after the birth of a severely affected family member.\n\nMost people with nonsyndromic holoprosencephaly have developmental delay and intellectual disability. Affected individuals also frequently have a malfunctioning pituitary gland, which is a gland located at the base of the brain that produces several hormones. Because pituitary dysfunction leads to the partial or complete absence of these hormones, it can cause a variety of disorders. Most commonly, people with nonsyndromic holoprosencephaly and pituitary dysfunction develop diabetes insipidus, a condition that disrupts the balance between fluid intake and urine excretion. Dysfunction in other parts of the brain can cause seizures, feeding difficulties, and problems regulating body temperature, heart rate, and breathing. The sense of smell may be diminished (hyposmia) or completely absent (anosmia) if the part of the brain that processes smells is underdeveloped or missing.
Global brain atrophy
MedGen UID:
66840
Concept ID:
C0241816
Pathologic Function
Unlocalized atrophy of the brain with decreased total brain matter volume and increased ventricular size.
Hypoplasia of the corpus callosum
MedGen UID:
138005
Concept ID:
C0344482
Congenital Abnormality
Underdevelopment of the corpus callosum.
Hyperactivity
MedGen UID:
98406
Concept ID:
C0424295
Finding
Hyperactivity is a condition characterized by constant and unusually high levels of activity, even in situations where it is deemed inappropriate.
Partial agenesis of the corpus callosum
MedGen UID:
98127
Concept ID:
C0431368
Congenital Abnormality
A partial failure of the development of the corpus callosum.
Colpocephaly
MedGen UID:
98131
Concept ID:
C0431384
Congenital Abnormality
Colpocephaly is an anatomic finding in the brain manifested by occipital horns that are disproportionately enlarged in comparison with other parts of the lateral ventricles.
Global developmental delay
MedGen UID:
107838
Concept ID:
C0557874
Finding
A delay in the achievement of motor or mental milestones in the domains of development of a child, including motor skills, speech and language, cognitive skills, and social and emotional skills. This term should only be used to describe children younger than five years of age.
Diffuse cerebral atrophy
MedGen UID:
108958
Concept ID:
C0598275
Finding
Diffuse unlocalised atrophy affecting the cerebrum.
Cerebellar atrophy
MedGen UID:
196624
Concept ID:
C0740279
Disease or Syndrome
Cerebellar atrophy is defined as a cerebellum with initially normal structures, in a posterior fossa with normal size, which displays enlarged fissures (interfolial spaces) in comparison to the foliae secondary to loss of tissue. Cerebellar atrophy implies irreversible loss of tissue and result from an ongoing progressive disease until a final stage is reached or a single injury, e.g. an intoxication or infectious event.
Chiari type I malformation
MedGen UID:
196689
Concept ID:
C0750929
Congenital Abnormality
Arnold-Chiari type I malformation refers to a relatively mild degree of herniation of the posteroinferior region of the cerebellum (the cerebellar tonsils) into the cervical canal with little or no displacement of the fourth ventricle. It is characterized by one or both pointed (not rounded) cerebellar tonsils that project 5 mm below the foramen magnum, measured by a line drawn from the basion to the opisthion (McRae Line)
Sleep-wake cycle disturbance
MedGen UID:
371548
Concept ID:
C1833362
Finding
Any abnormality of an individual's circadian rhythm that affects the timing of sleeping and being awake is referred to as a sleep-wake disorder.
Hypoplasia of the frontal lobes
MedGen UID:
341396
Concept ID:
C1849172
Finding
Underdevelopment of the frontal lobe of the cerebrum.
Intellectual disability
MedGen UID:
811461
Concept ID:
C3714756
Mental or Behavioral Dysfunction
Intellectual disability, previously referred to as mental retardation, is characterized by subnormal intellectual functioning that occurs during the developmental period. It is defined by an IQ score below 70.
Periventricular heterotopia
MedGen UID:
1766888
Concept ID:
C5399973
Disease or Syndrome
A form of gray matter heterotopia were the mislocalized gray matter is typically located periventricularly, also sometimes called subependymal heterotopia. Periventricular means beside the ventricles. This is by far the most common location for heterotopia. Subependymal heterotopia present in a wide array of variations. There can be a small single node or a large number of nodes, can exist on either or both sides of the brain at any point along the higher ventricle margins, can be small or large, single or multiple, and can form a small node or a large wavy or curved mass.
Dandy-Walker syndrome
MedGen UID:
4150
Concept ID:
C0010964
Disease or Syndrome
Dandy-Walker malformation is defined by hypoplasia and upward rotation of the cerebellar vermis and cystic dilation of the fourth ventricle. Affected individuals often have motor deficits such as delayed motor development, hypotonia, and ataxia; about half have mental retardation and some have hydrocephalus. DWM is a heterogeneous disorder. The low empiric recurrence risk of approximately 1 to 2% for nonsyndromic DWM suggests that mendelian inheritance is unlikely (summary by Murray et al., 1985).
Hip dislocation
MedGen UID:
42455
Concept ID:
C0019554
Injury or Poisoning
Displacement of the femur from its normal location in the hip joint.
Micrognathia
MedGen UID:
44428
Concept ID:
C0025990
Congenital Abnormality
Developmental hypoplasia of the mandible.
Hypertonia
MedGen UID:
10132
Concept ID:
C0026826
Finding
A condition in which there is increased muscle tone so that arms or legs, for example, are stiff and difficult to move.
Hypotonia
MedGen UID:
10133
Concept ID:
C0026827
Finding
Hypotonia is an abnormally low muscle tone (the amount of tension or resistance to movement in a muscle). Even when relaxed, muscles have a continuous and passive partial contraction which provides some resistance to passive stretching. Hypotonia thus manifests as diminished resistance to passive stretching. Hypotonia is not the same as muscle weakness, although the two conditions can co-exist.
Microretrognathia
MedGen UID:
326907
Concept ID:
C1839546
Finding
A form of developmental hypoplasia of the mandible in which the mandible is mislocalised posteriorly.
Generalized hypotonia
MedGen UID:
346841
Concept ID:
C1858120
Finding
Generalized muscular hypotonia (abnormally low muscle tone).
Epiphyseal stippling
MedGen UID:
349104
Concept ID:
C1859126
Finding
The presence of abnormal punctate (speckled, dot-like) calcifications in one or more epiphyses.
Microcephaly
MedGen UID:
1644158
Concept ID:
C4551563
Finding
Head circumference below 2 standard deviations below the mean for age and gender.
Pulmonary hypoplasia
MedGen UID:
78574
Concept ID:
C0265783
Congenital Abnormality
A congenital abnormality in which the lung parenchyma is not fully developed. It may be associated with other congenital abnormalities.
Abnormal lung lobation
MedGen UID:
195782
Concept ID:
C0685695
Congenital Abnormality
A developmental defect in the formation of pulmonary lobes.
Eczematoid dermatitis
MedGen UID:
3968
Concept ID:
C0013595
Disease or Syndrome
Eczema is a form of dermatitis that is characterized by scaly, pruritic, erythematous lesions located on flexural surfaces.
Splenomegaly
MedGen UID:
52469
Concept ID:
C0038002
Finding
Abnormal increased size of the spleen.
Recurrent otitis media
MedGen UID:
155436
Concept ID:
C0747085
Disease or Syndrome
Increased susceptibility to otitis media, as manifested by recurrent episodes of otitis media.
Hypocholesterolemia
MedGen UID:
57479
Concept ID:
C0151718
Disease or Syndrome
An decreased concentration of cholesterol in the blood.
Hypoalbuminemia
MedGen UID:
68694
Concept ID:
C0239981
Finding
Reduction in the concentration of albumin in the blood.
Elevated circulating 7-dehydrocholesterol concentration
MedGen UID:
376537
Concept ID:
C1849185
Finding
Concentration of 7-dehydrocholesterol in the blood circulation above the upper limit of normal.
Microglossia
MedGen UID:
10029
Concept ID:
C0025988
Congenital Abnormality
Decreased length and width of the tongue.
Dental crowding
MedGen UID:
11850
Concept ID:
C0040433
Finding
Changes in alignment of teeth in the dental arch
Epicanthus
MedGen UID:
151862
Concept ID:
C0678230
Congenital Abnormality
Epicanthus is a condition in which a fold of skin stretches from the upper to the lower eyelid, partially covering the inner canthus. Usher (1935) noted that epicanthus is a normal finding in the fetus of all races. Epicanthus also occurs in association with hereditary ptosis (110100).
Depressed nasal bridge
MedGen UID:
373112
Concept ID:
C1836542
Finding
Posterior positioning of the nasal root in relation to the overall facial profile for age.
Narrow forehead
MedGen UID:
326956
Concept ID:
C1839758
Finding
Width of the forehead or distance between the frontotemporales is more than two standard deviations below the mean (objective); or apparently narrow intertemporal region (subjective).
Anteverted nares
MedGen UID:
326648
Concept ID:
C1840077
Finding
Anteriorly-facing nostrils viewed with the head in the Frankfurt horizontal and the eyes of the observer level with the eyes of the subject. This gives the appearance of an upturned nose (upturned nasal tip).
Wide nasal bridge
MedGen UID:
341441
Concept ID:
C1849367
Finding
Increased breadth of the nasal bridge (and with it, the nasal root).
Broad alveolar ridges
MedGen UID:
347470
Concept ID:
C1857500
Finding
Long philtrum
MedGen UID:
351278
Concept ID:
C1865014
Finding
Distance between nasal base and midline upper lip vermilion border more than 2 SD above the mean. Alternatively, an apparently increased distance between nasal base and midline upper lip vermilion border.
Cleft palate
MedGen UID:
756015
Concept ID:
C2981150
Congenital Abnormality
Cleft palate is a developmental defect of the palate resulting from a failure of fusion of the palatine processes and manifesting as a separation of the roof of the mouth (soft and hard palate).
Bifid uvula
MedGen UID:
1646931
Concept ID:
C4551488
Congenital Abnormality
Uvula separated into two parts most easily seen at the tip.
Sacral dimple
MedGen UID:
98428
Concept ID:
C0426848
Finding
A cutaneous indentation resulting from tethering of the skin to underlying structures (bone) of the intergluteal cleft.
Severe photosensitivity
MedGen UID:
341399
Concept ID:
C1849186
Finding
A severe degree of photosensitivity of the skin.
Breech presentation
MedGen UID:
654
Concept ID:
C0006157
Pathologic Function
A position of the fetus at delivery in which the fetus enters the birth canal with the buttocks or feet first.
Premature birth
MedGen UID:
57721
Concept ID:
C0151526
Pathologic Function
The birth of a baby of less than 37 weeks of gestational age.
Decreased fetal movement
MedGen UID:
68618
Concept ID:
C0235659
Finding
An abnormal reduction in quantity or strength of fetal movements.
Precocious puberty
MedGen UID:
18752
Concept ID:
C0034013
Disease or Syndrome
The onset of secondary sexual characteristics before a normal age. Although it is difficult to define normal age ranges because of the marked variation with which puberty begins in normal children, precocious puberty can be defined as the onset of puberty before the age of 8 years in girls or 9 years in boys.
Ptosis
MedGen UID:
2287
Concept ID:
C0005745
Disease or Syndrome
The upper eyelid margin is positioned 3 mm or more lower than usual and covers the superior portion of the iris (objective); or, the upper lid margin obscures at least part of the pupil (subjective).
Hypertelorism
MedGen UID:
9373
Concept ID:
C0020534
Finding
Although hypertelorism means an excessive distance between any paired organs (e.g., the nipples), the use of the word has come to be confined to ocular hypertelorism. Hypertelorism occurs as an isolated feature and is also a feature of many syndromes, e.g., Opitz G syndrome (see 300000), Greig cephalopolysyndactyly (175700), and Noonan syndrome (163950) (summary by Cohen et al., 1995).
Nystagmus
MedGen UID:
45166
Concept ID:
C0028738
Disease or Syndrome
Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms.
Strabismus
MedGen UID:
21337
Concept ID:
C0038379
Disease or Syndrome
A misalignment of the eyes so that the visual axes deviate from bifoveal fixation. The classification of strabismus may be based on a number of features including the relative position of the eyes, whether the deviation is latent or manifest, intermittent or constant, concomitant or otherwise and according to the age of onset and the relevance of any associated refractive error.
Cataract
MedGen UID:
39462
Concept ID:
C0086543
Disease or Syndrome
A cataract is an opacity or clouding that develops in the crystalline lens of the eye or in its capsule.

Term Hierarchy

CClinical test,  RResearch test,  OOMIM,  GGeneReviews,  VClinVar  
  • CROGVSmith-Lemli-Opitz syndrome
Follow this link to review classifications for Smith-Lemli-Opitz syndrome in Orphanet.

Professional guidelines

PubMed

Svoboda MD, Christie JM, Eroglu Y, Freeman KA, Steiner RD
Am J Med Genet C Semin Med Genet 2012 Nov 15;160C(4):285-94. Epub 2012 Oct 5 doi: 10.1002/ajmg.c.31347. PMID: 23042642Free PMC Article
Porter FD
Eur J Hum Genet 2008 May;16(5):535-41. Epub 2008 Feb 20 doi: 10.1038/ejhg.2008.10. PMID: 18285838
Chen CP
Taiwan J Obstet Gynecol 2007 Mar;46(1):9-14. doi: 10.1016/S1028-4559(08)60100-X. PMID: 17389183

Recent clinical studies

Etiology

Ballout RA, Livinski A, Fu YP, Steiner RD, Remaley AT
Cochrane Database Syst Rev 2022 Nov 14;11(11):CD013521. doi: 10.1002/14651858.CD013521.pub2. PMID: 36373961Free PMC Article
Zalewski CK, Sydlowski SA, King KA, Bianconi S, Dang Do A, Porter FD, Brewer CC
Am J Med Genet A 2021 Apr;185(4):1131-1141. Epub 2021 Feb 2 doi: 10.1002/ajmg.a.62087. PMID: 33529473Free PMC Article
DeBarber AE, Eroglu Y, Merkens LS, Pappu AS, Steiner RD
Expert Rev Mol Med 2011 Jul 22;13:e24. doi: 10.1017/S146239941100189X. PMID: 21777499Free PMC Article
Kelley RI, Hennekam RC
J Med Genet 2000 May;37(5):321-35. doi: 10.1136/jmg.37.5.321. PMID: 10807690Free PMC Article
Opitz JM
Curr Opin Pediatr 1999 Aug;11(4):353-62. doi: 10.1097/00008480-199908000-00015. PMID: 10439210

Diagnosis

Ballout RA, Livinski A, Fu YP, Steiner RD, Remaley AT
Cochrane Database Syst Rev 2022 Nov 14;11(11):CD013521. doi: 10.1002/14651858.CD013521.pub2. PMID: 36373961Free PMC Article
Zalewski CK, Sydlowski SA, King KA, Bianconi S, Dang Do A, Porter FD, Brewer CC
Am J Med Genet A 2021 Apr;185(4):1131-1141. Epub 2021 Feb 2 doi: 10.1002/ajmg.a.62087. PMID: 33529473Free PMC Article
Society for Maternal-Fetal Medicine, Rac MWF, McKinney J, Gandhi M
Am J Obstet Gynecol 2019 Dec;221(6):B13-B15. doi: 10.1016/j.ajog.2019.09.023. PMID: 31787158
Kelley RI, Hennekam RC
J Med Genet 2000 May;37(5):321-35. doi: 10.1136/jmg.37.5.321. PMID: 10807690Free PMC Article
Opitz JM
Curr Opin Pediatr 1999 Aug;11(4):353-62. doi: 10.1097/00008480-199908000-00015. PMID: 10439210

Therapy

Ballout RA, Livinski A, Fu YP, Steiner RD, Remaley AT
Cochrane Database Syst Rev 2022 Nov 14;11(11):CD013521. doi: 10.1002/14651858.CD013521.pub2. PMID: 36373961Free PMC Article
Schaefer EJ, Tint GS, Duell PB, Steiner RD
J Clin Lipidol 2021 Jul-Aug;15(4):540-544. Epub 2021 May 28 doi: 10.1016/j.jacl.2021.05.004. PMID: 34140251
Svoboda MD, Christie JM, Eroglu Y, Freeman KA, Steiner RD
Am J Med Genet C Semin Med Genet 2012 Nov 15;160C(4):285-94. Epub 2012 Oct 5 doi: 10.1002/ajmg.c.31347. PMID: 23042642Free PMC Article
Tierney E, Nwokoro NA, Kelley RI
Ment Retard Dev Disabil Res Rev 2000;6(2):131-4. doi: 10.1002/1098-2779(2000)6:2<131::AID-MRDD7>3.0.CO;2-R. PMID: 10899806
Sinclair L, Winterborn MH, Brown J
Proc R Soc Med 1969 Sep;62(9):907-8. PMID: 5349196Free PMC Article

Prognosis

López-Cañizares A, Al-Khersan H, Fernandez MP, Lin BR, Goduni L, Berrocal AM
J AAPOS 2023 Apr;27(2):100-102. Epub 2022 Dec 21 doi: 10.1016/j.jaapos.2022.11.007. PMID: 36563894
Society for Maternal-Fetal Medicine, Rac MWF, McKinney J, Gandhi M
Am J Obstet Gynecol 2019 Dec;221(6):B13-B15. doi: 10.1016/j.ajog.2019.09.023. PMID: 31787158
Donoghue SE, Pitt JJ, Boneh A, White SM
J Pediatr Endocrinol Metab 2018 Mar 28;31(4):451-459. doi: 10.1515/jpem-2017-0501. PMID: 29455191
Movassaghi M, Bianconi S, Feinn R, Wassif CA, Porter FD
Am J Med Genet A 2017 Oct;173(10):2577-2583. Epub 2017 Aug 10 doi: 10.1002/ajmg.a.38361. PMID: 28796426Free PMC Article
Lazarin GA, Haque IS, Evans EA, Goldberg JD
Prenat Diagn 2017 Apr;37(4):350-355. Epub 2017 Mar 9 doi: 10.1002/pd.5018. PMID: 28166604Free PMC Article

Clinical prediction guides

Koczok K, Horváth L, Korade Z, Mezei ZA, Szabó GP, Porter NA, Kovács E, Mirnics K, Balogh I
Biomolecules 2021 Aug 17;11(8) doi: 10.3390/biom11081228. PMID: 34439893Free PMC Article
Zalewski CK, Sydlowski SA, King KA, Bianconi S, Dang Do A, Porter FD, Brewer CC
Am J Med Genet A 2021 Apr;185(4):1131-1141. Epub 2021 Feb 2 doi: 10.1002/ajmg.a.62087. PMID: 33529473Free PMC Article
Eroglu Y, Nguyen-Driver M, Steiner RD, Merkens L, Merkens M, Roullet JB, Elias E, Sarphare G, Porter FD, Li C, Tierney E, Nowaczyk MJ, Freeman KA
Am J Med Genet A 2017 Aug;173(8):2097-2100. Epub 2017 Mar 27 doi: 10.1002/ajmg.a.38125. PMID: 28349652Free PMC Article
Lazarin GA, Haque IS, Evans EA, Goldberg JD
Prenat Diagn 2017 Apr;37(4):350-355. Epub 2017 Mar 9 doi: 10.1002/pd.5018. PMID: 28166604Free PMC Article
Opitz JM, Furtado LV
Am J Med Genet C Semin Med Genet 2012 Nov 15;160C(4):242-9. Epub 2012 Oct 11 doi: 10.1002/ajmg.c.31341. PMID: 23059855

Recent systematic reviews

Ballout RA, Livinski A, Fu YP, Steiner RD, Remaley AT
Cochrane Database Syst Rev 2022 Nov 14;11(11):CD013521. doi: 10.1002/14651858.CD013521.pub2. PMID: 36373961Free PMC Article
Pantel JT, Zhao M, Mensah MA, Hajjir N, Hsieh TC, Hanani Y, Fleischer N, Kamphans T, Mundlos S, Gurovich Y, Krawitz PM
J Inherit Metab Dis 2018 May;41(3):533-539. Epub 2018 Apr 5 doi: 10.1007/s10545-018-0174-3. PMID: 29623569Free PMC Article
Boland MR, Tatonetti NP
Pharmacogenomics J 2016 Oct;16(5):411-29. Epub 2016 Jul 12 doi: 10.1038/tpj.2016.48. PMID: 27401223Free PMC Article