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Hyperphosphatasia with intellectual disability syndrome 2(HPMRS2)

MedGen UID:
766551
Concept ID:
C3553637
Disease or Syndrome
Synonyms: GLYCOSYLPHOSPHATIDYLINOSITOL BIOSYNTHESIS DEFECT 6; HPMRS2; HYPERPHOSPHATASIA WITH IMPAIRED INTELLECTUAL DEVELOPMENT SYNDROME 2
 
Gene (location): PIGO (9p13.3)
 
Monarch Initiative: MONDO:0013882
OMIM®: 614749

Definition

Hyperphosphatasia with impaired intellectual development syndrome-2 (HPMRS2) is an autosomal recessive disorder characterized by moderately to severely delayed psychomotor development, facial dysmorphism, brachytelephalangy, and increased serum alkaline phosphatase (hyperphosphatasia). Some patients may have additional features, such as cardiac septal defects or seizures (summary by Krawitz et al., 2012). The disorder is caused by a defect in glycosylphosphatidylinositol (GPI) biosynthesis. For a discussion of genetic heterogeneity of hyperphosphatasia with impaired intellectual development syndrome, see HPMRS1 (239300). For a discussion of genetic heterogeneity of GPI biosynthesis defects, see GPIBD1 (610293). [from OMIM]

Additional description

From MedlinePlus Genetics
Mabry syndrome is a condition characterized by intellectual disability, distinctive facial features, increased levels of an enzyme called alkaline phosphatase in the blood (hyperphosphatasia), and other signs and symptoms.

People with Mabry syndrome have intellectual disability that is often moderate to severe. They typically have little to no speech development and are delayed in the development of motor skills (such as sitting, crawling, and walking). Many affected individuals have low muscle tone (hypotonia) and develop recurrent seizures (epilepsy) in early childhood. Seizures are usually the generalized tonic-clonic type, which involve muscle rigidity, convulsions, and loss of consciousness.

The signs and symptoms of Mabry syndrome vary among affected individuals. Those who are least severely affected have only intellectual disability and hyperphosphatasia, without distinctive facial features or the other health problems listed above.

Individuals with Mabry syndrome have distinctive facial features that include wide-set eyes (hypertelorism), long openings of the eyelids (long palpebral fissures), a nose with a broad bridge and a rounded tip, downturned corners of the mouth, and a thin upper lip. These facial features usually become less pronounced over time.

Hyperphosphatasia begins within the first year of life in people with Mabry syndrome. There are many different types of alkaline phosphatase found in tissues; the type that is increased in Mabry syndrome is called the tissue non-specific type and is found throughout the body. In affected individuals, alkaline phosphatase levels in the blood are usually increased by one to two times the normal amount, but can be up to 20 times higher than normal. The elevated enzyme levels remain relatively stable over a person's lifetime. Hyperphosphatasia appears to cause no negative health effects, but this finding can help health professionals diagnose Mabry syndrome.

Another common feature of Mabry syndrome is shortened bones at the ends of fingers (brachytelephalangy), which can be seen on x-ray imaging. Underdeveloped fingernails (nail hypoplasia) may also occur. Sometimes, individuals with Mabry syndrome have abnormalities of the digestive system, including narrowing or blockage of the anus (anal stenosis or anal atresia) or Hirschsprung disease, a disorder that causes severe constipation or blockage of the intestine. Rarely, affected individuals experience hearing loss.  https://medlineplus.gov/genetics/condition/mabry-syndrome

Clinical features

From HPO
Vesicoureteral reflux
MedGen UID:
21852
Concept ID:
C0042580
Disease or Syndrome
Vesicoureteral reflux (VUR) is characterized by the reflux of urine from the bladder into the ureters and sometimes into the kidneys. It is a risk factor for urinary tract infections. Primary VUR results from a developmental defect of the ureterovesical junction (UVJ). In combination with intrarenal reflux, the resulting inflammatory reaction may result in renal injury or scarring, also called reflux nephropathy (RN). Extensive renal scarring impairs renal function and may predispose patients to hypertension, proteinuria, and renal insufficiency (summary by Lu et al., 2007). Genetic Heterogeneity of Vesicoureteral Reflux A locus designated VUR1 maps to chromosome 1p13. VUR2 (610878) is caused by mutation in the ROBO2 gene (602431) on chromosome 3p12; VUR3 (613674) is caused by mutation in the SOX17 gene (610928) on chromosome 8q11; VUR4 (614317) maps to chromosome 5; VUR5 (614318) maps to chromosome 13; VUR6 (614319) maps to chromosome 18; VUR7 (615390) maps to chromosome 12; and VUR8 (615963) is caused by mutation in the TNXB gene (600985) on chromosome 6p21. A possible X-linked form has been reported (VURX; 314550).
Broad hallux
MedGen UID:
401165
Concept ID:
C1867131
Finding
Visible increase in width of the hallux without an increase in the dorso-ventral dimension.
Shortening of all distal phalanges of the fingers
MedGen UID:
867248
Concept ID:
C4021608
Finding
Hypoplasia of all of the distal phalanx of finger.
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.
Peripheral pulmonary artery stenosis
MedGen UID:
138014
Concept ID:
C0345030
Finding
Stenosis of a peripheral branch of the pulmonary artery.
Growth delay
MedGen UID:
99124
Concept ID:
C0456070
Pathologic Function
A deficiency or slowing down of growth pre- and postnatally.
Imperforate anus
MedGen UID:
1997
Concept ID:
C0003466
Congenital Abnormality
Congenital absence of the anus, i.e., the opening at the bottom end of the intestinal tract.
Anal stenosis
MedGen UID:
82644
Concept ID:
C0262374
Anatomical Abnormality
Abnormal narrowing of the anal opening.
Hearing impairment
MedGen UID:
235586
Concept ID:
C1384666
Disease or Syndrome
A decreased magnitude of the sensory perception of sound.
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).
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.
Delayed ability to walk
MedGen UID:
66034
Concept ID:
C0241726
Finding
A failure to achieve the ability to walk at an appropriate developmental stage. Most children learn to walk in a series of stages, and learn to walk short distances independently between 12 and 15 months.
Delayed speech and language development
MedGen UID:
105318
Concept ID:
C0454644
Finding
A degree of language development that is significantly below the norm for a child of a specified age.
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.
Ventriculomegaly
MedGen UID:
480553
Concept ID:
C3278923
Finding
An increase in size of the ventricular system of the brain.
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.
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.
Plagiocephaly
MedGen UID:
1825944
Concept ID:
C2081594
Finding
Asymmetric head shape, which is usually a combination of unilateral occipital flattening with ipsilateral frontal prominence, leading to rhomboid cranial shape.
Anterior plagiocephaly
MedGen UID:
868997
Concept ID:
C4023413
Finding
Asymmetry of the anterior part of the skull.
Left unicoronal synostosis
MedGen UID:
869001
Concept ID:
C4023417
Anatomical Abnormality
Synostosis affecting only the left coronal suture.
Microcephaly
MedGen UID:
1644158
Concept ID:
C4551563
Finding
Head circumference below 2 standard deviations below the mean for age and gender.
Elevated circulating alkaline phosphatase concentration
MedGen UID:
727252
Concept ID:
C1314665
Finding
Abnormally increased serum levels of alkaline phosphatase activity.
Upslanted palpebral fissure
MedGen UID:
98390
Concept ID:
C0423109
Finding
The palpebral fissure inclination is more than two standard deviations above the mean for age (objective); or, the inclination of the palpebral fissure is greater than typical for age.
Broad nasal tip
MedGen UID:
98424
Concept ID:
C0426429
Finding
Increase in width of the nasal tip.
Tented upper lip vermilion
MedGen UID:
326574
Concept ID:
C1839767
Finding
Triangular appearance of the oral aperture with the apex in the midpoint of the upper vermilion and the lower vermilion forming the base.
Long palpebral fissure
MedGen UID:
340300
Concept ID:
C1849340
Finding
Distance between medial and lateral canthi is more than two standard deviations above the mean for age (objective); or, apparently increased length of the palpebral fissures.
Wide nasal bridge
MedGen UID:
341441
Concept ID:
C1849367
Finding
Increased breadth of the nasal bridge (and with it, the nasal root).
Short nose
MedGen UID:
343052
Concept ID:
C1854114
Finding
Distance from nasion to subnasale more than two standard deviations below the mean, or alternatively, an apparently decreased length from the nasal root to the nasal tip.
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).
Hypoplastic fingernail
MedGen UID:
347304
Concept ID:
C1856786
Finding
Underdevelopment of a fingernail.
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).

Recent clinical studies

Etiology

Horn D, Wieczorek D, Metcalfe K, Barić I, Paležac L, Cuk M, Petković Ramadža D, Krüger U, Demuth S, Heinritz W, Linden T, Koenig J, Robinson PN, Krawitz P
Eur J Hum Genet 2014 Jun;22(6):762-7. Epub 2013 Oct 16 doi: 10.1038/ejhg.2013.241. PMID: 24129430Free PMC Article

Diagnosis

Winter-Paquette LM, Al Suwaidi HH, Sajjad Y, Bricker L
Eur J Med Genet 2022 May;65(5):104501. Epub 2022 Apr 1 doi: 10.1016/j.ejmg.2022.104501. PMID: 35378319
Xue J, Li H, Zhang Y, Yang Z
Brain Dev 2016 Oct;38(9):807-18. Epub 2016 May 10 doi: 10.1016/j.braindev.2016.04.008. PMID: 27177984
Horn D, Wieczorek D, Metcalfe K, Barić I, Paležac L, Cuk M, Petković Ramadža D, Krüger U, Demuth S, Heinritz W, Linden T, Koenig J, Robinson PN, Krawitz P
Eur J Hum Genet 2014 Jun;22(6):762-7. Epub 2013 Oct 16 doi: 10.1038/ejhg.2013.241. PMID: 24129430Free PMC Article
Horn D, Krawitz P, Mannhardt A, Korenke GC, Meinecke P
Am J Med Genet A 2011 Aug;155A(8):1917-22. Epub 2011 Jul 7 doi: 10.1002/ajmg.a.34102. PMID: 21739589
Horn D, Schottmann G, Meinecke P
Eur J Med Genet 2010 Mar-Apr;53(2):85-8. Epub 2010 Jan 18 doi: 10.1016/j.ejmg.2010.01.002. PMID: 20080219

Prognosis

Nakamura K, Osaka H, Murakami Y, Anzai R, Nishiyama K, Kodera H, Nakashima M, Tsurusaki Y, Miyake N, Kinoshita T, Matsumoto N, Saitsu H
Epilepsia 2014 Feb;55(2):e13-7. Epub 2014 Jan 13 doi: 10.1111/epi.12508. PMID: 24417746

Clinical prediction guides

Winter-Paquette LM, Al Suwaidi HH, Sajjad Y, Bricker L
Eur J Med Genet 2022 May;65(5):104501. Epub 2022 Apr 1 doi: 10.1016/j.ejmg.2022.104501. PMID: 35378319
Xue J, Li H, Zhang Y, Yang Z
Brain Dev 2016 Oct;38(9):807-18. Epub 2016 May 10 doi: 10.1016/j.braindev.2016.04.008. PMID: 27177984

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