MedGen

ARCND2B is characterized by the typical features of auriculocondylar syndrome, including the pathognomonic question mark ears, consisting of a variable degree of clefting between the helix and earlobe, as well as hypoplasia of the mandibular condyle, temporomandibular joint abnormalities, micrognathia, microstomia, glossoptosis, and a round facial appearance with prominent cheeks. Patients have difficulty chewing, respiratory abnormalities, snoring, and obstructive and central apneas. In addition, they experience severe gastrointestinal problems, including feeding difficulties with failure to thrive, gastroesophageal reflux, and chronic constipation, and male patients show macropenis whereas female patients may exhibit clitoromegaly (summary by Leoni et al., 2016). Heterozygous mutation in the PLCB4 gene also causes an autosomal dominant form of auriculocondylar syndrome (see ARCND2A, 614669). For a discussion of genetic heterogeneity of auriculocondylar syndrome, see ARCND1 (602483). [from OMIM]

Congenital myopathy-20 (CMYP20) is an autosomal recessive neuromuscular disorder that shows wide phenotypic variability. Some patients present in early childhood with proximal muscle weakness affecting the lower and upper limbs resulting in difficulties running and climbing, whereas others present soon after birth with congenital limb or distal contractures. Additional features may include dysmorphic facial features and global developmental delay. Skeletal muscle biopsy may show nemaline rods (Nilipour et al., 2018; Pehlivan et al., 2019). For a discussion of genetic heterogeneity of congenital myopathy, see CMYP1A (117000). [from OMIM]

An instance of renal tubular dysgenesis that is caused by a modification of the individual's genome. [from MONDO]

Charcot-Marie-Tooth disease type 1J (CMT1J) is an autosomal dominant sensorimotor peripheral neuropathy characterized by distal muscle weakness and atrophy, as well as distal sensory impairment, predominantly affecting the lower limbs and resulting in gait abnormalities. The age at onset is highly variable, ranging from early childhood to mid-adulthood, and the disorder is progressive, although the severity is also variable. Additional features may include foot deformities, upper limb or hand involvement, and decreased or absent deep tendon reflexes. Electrophysiologic studies tend to show nerve conduction velocities in the demyelinating range, although some patients may have results in the intermediate range, likely reflecting secondary axonal degeneration (summary by Ronkko et al., 2020). For a discussion of genetic heterogeneity of autosomal dominant Charcot-Marie-Tooth disease type 1, see CMT1B (118200). [from OMIM]

Neurodevelopmental disorder with hypotonia, impaired speech, and behavioral abnormalities (NEDHISB) is characterized by global developmental delay apparent since infancy or early childhood, hypotonia with delayed motor development, impaired intellectual development with significant speech delay or absent speech, and variable behavioral abnormalities, such as autism, repetitive actions, or aggression. About two-thirds of patients have early-onset seizures that range from intractable to self-limiting. More variable features include nonspecific dysmorphic facial features, distal skeletal anomalies, and brain imaging abnormalities. The phenotypic manifestations and severity are highly variable (Muir et al., 2021). [from OMIM]

Preeclampsia, which along with chronic hypertension and gestational hypertension comprise the hypertensive disorders of pregnancy, is characterized by new hypertension (blood pressure 140/90 or greater) presenting after 20 weeks' gestation with clinically relevant proteinuria. Preeclampsia is 1 of the top 4 causes of maternal mortality and morbidity worldwide (summary by Payne et al., 2011). Preeclampsia is otherwise known as gestational proteinuric hypertension (Davey and MacGillivray, 1988). A high proportion of patients with preeclampsia have glomerular endotheliosis, the unique histopathologic feature of the condition (Fisher et al., 1981). A distinct form of severe preeclampsia is characterized by hemolysis, elevated liver enzymes, and low platelets (HELLP syndrome) (Brown et al., 2000). Genetic Heterogeneity of Preeclampsia/Eclampsia Susceptibility loci for preeclampsia/eclampsia include PEE1 on chromosome 2p13, PEE2 (609402) on chromosome 2p25, and PEE3 (609403) on chromosome 9p13. PEE4 (609404) is caused by mutation in the STOX1 gene (609397) on chromosome 10q22. PEE5 (614595) is caused by mutation in the CORIN gene (605236) on chromosome 4p12. An association with PEE has been found with the EPHX1 gene (132810) on chromosome 1q. [from OMIM]

Neurodevelopmental disorder with central hypotonia and dysmorphic facies (NEDCHF) is an autosomal dominant disorder characterized by global developmental delay, impaired intellectual development, seizures, distinctive facial features, scoliosis, delayed closure of the anterior fontanel, and nonspecific brain abnormalities (Wakeling et al., 2021). [from OMIM]

Immunodeficiency-97 with autoinflammation (IMD97) is an autosomal recessive complex immunologic disorder with variable features. Affected individuals present in the first decade of life with inflammatory interstitial lung disease or colitis due to abnormal tissue infiltration by activated T cells. Patients develop autoimmune cytopenias and may have lymphadenopathy; 1 reported patient had features of hemophagocytic lymphohistiocytosis (HLH; see FHL1, 267700). Some patients may have recurrent infections associated with mild lymphopenia, hypogammaglobulinemia, and NK cell dysfunction. Immunologic workup indicates signs of significant immune dysregulation with elevation of inflammatory serum markers, variable immune cell defects involving neutrophils, NK cells, and myeloid cells, and disrupted levels of T regulatory cells (Tregs). Two unrelated patients have been reported (summary by Takeda et al., 2019 and Thian et al., 2020). [from OMIM]

GNB5-related neurodevelopmental disorder (GNB5-NDD) is characterized by a spectrum of neurodevelopmental phenotypes that range from severe-to-profound intellectual disability (ID; 31/41 reported individuals), to mild-to-moderate ID (5/41), to normal intellect with severe language disorder (5/41, one extended family). A unique and specific feature of GNB5-NDD – regardless of neurodevelopmental phenotype – is nearly universal bradycardia caused by sinoatrial node dysfunction (sick sinus syndrome). Most individuals with severe and profound ID have a developmental and epileptic encephalopathy with focal seizures or epileptic spasms, as well as visual impairment (central or retinal) with nystagmus, difficulty feeding, and gastroesophageal reflux disease. The risk of early mortality is increased. [from GeneReviews]

Isolated anhidrosis with normal sweat glands (ANHD) is characterized by absence of perspiration and subsequent heat intolerance with normal morphology and number of sweat glands. Teeth, hair, nails, and skin are normal (Klar et al., 2014). [from OMIM]

Multiple types of congenital heart defects-8 (CHTD8) is characterized by cardiac septal defects, double-outlet right ventricle, unbalanced complete atrioventricular canal, and valvular anomalies, as well as vascular anomalies including dextroposition of the great arteries, anomalous pulmonary venous return, and superior vena cava to left atrium defect. Patients may also exhibit laterality defects, including dextrocardia, atrial isomerism, dextrogastria, left-sided gallbladder, and intestinal malrotation (Zaidi et al., 2013; Granadillo et al., 2018). [from OMIM]

Loeys-Dietz syndrome (LDS) is characterized by vascular findings (cerebral, thoracic, and abdominal arterial aneurysms and/or dissections), skeletal manifestations (pectus excavatum or pectus carinatum, scoliosis, joint laxity, arachnodactyly, talipes equinovarus, cervical spine malformation and/or instability), craniofacial features (widely spaced eyes, strabismus, bifid uvula / cleft palate, and craniosynostosis that can involve any sutures), and cutaneous findings (velvety and translucent skin, easy bruising, and dystrophic scars). Individuals with LDS are predisposed to widespread and aggressive arterial aneurysms and pregnancy-related complications including uterine rupture and death. Individuals with LDS can show a strong predisposition for allergic/inflammatory disease including asthma, eczema, and reactions to food or environmental allergens. There is also an increased incidence of gastrointestinal inflammation including eosinophilic esophagitis and gastritis or inflammatory bowel disease. Wide variation in the distribution and severity of clinical features can be seen in individuals with LDS, even among affected individuals within a family who have the same pathogenic variant. [from GeneReviews]

Neurodevelopmental disorder with hyperkinetic movements and dyskinesia (NEDHYD) is an autosomal recessive complex neurologic disorder characterized by severe global developmental delay with axial hypotonia, impaired intellectual development, poor overall growth, and abnormal involuntary hyperkinetic movements, including dystonia, myoclonus, spasticity, and orofacial dyskinesia. It is the most severe manifestation of ADCY5-related dyskinetic disorders (summary by Okamoto et al., 2021 and Kaiyrzhanov et al., 2021). [from OMIM]

Autosomal recessive dyskinesia with orofacial involvement (DSKOR) is characterized by the onset of abnormal involuntary movements, mainly affecting the limbs and causing walking difficulties, in the first decade. The severity is variable; some patients have orofacial dyskinesia resulting in speech difficulties, or develop neuropsychiatric features, including anxiety and social withdrawal. Cardiomyopathy has rarely been described and may be a manifestation of the disorder (summary by Bohlega et al., 2019). [from OMIM]

Axonal Charcot-Marie-Tooth disease type 2HH (CMT2HH) is an autosomal dominant peripheral neuropathy characterized predominantly by onset of vocal cord weakness resulting in stridor in infancy or early childhood. The vocal cord paresis remains throughout life and may be severe enough to require tracheostomy. Additional features of the disorder usually include pes cavus and scoliosis. Some patients have mild distal muscle weakness and atrophy primarily affecting the lower limbs, although the upper limbs may also be involved, and distal sensory impairment, often with hyporeflexia (Sullivan et al., 2020). For a discussion of genetic heterogeneity of axonal CMT, see CMT2A1 (118210). [from OMIM]

Autosomal recessive limb-girdle muscular dystrophy-27 (LGMDR27) is characterized by progressive muscle weakness primarily affecting the lower limbs and resulting in walking difficulty or loss of ambulation. The age at onset is highly variable, from infancy to young adulthood. Patients with infantile onset may have a more severe disease course with rapid progression. Upper limb involvement and distal muscle weakness may also occur. Additional more variable features include neck muscle weakness, scoliosis, and joint contractures. Less common features include impaired intellectual development or speech delay, cardiomyopathy, and cardiac arrhythmia. Muscle biopsy shows nonspecific dystrophic changes (Coppens et al., 2021). For a discussion of genetic heterogeneity of autosomal recessive limb-girdle muscular dystrophy, see LGMDR1 (253600). [from OMIM]

Neurodevelopmental disorder with hypotonia and dysmorphic facies (NEDHYDF) is characterized by global developmental delay and hypotonia apparent from birth. Affected individuals have variably impaired intellectual development, often with speech delay and delayed walking. Seizures are generally not observed, although some patients may have single seizures or late-onset epilepsy. Most patients have prominent dysmorphic facial features. Additional features may include congenital cardiac defects (without arrhythmia), nonspecific renal anomalies, joint contractures or joint hyperextensibility, dry skin, and cryptorchidism. There is significant phenotypic variability in both the neurologic and extraneurologic manifestations (summary by Tan et al., 2022). [from OMIM]

Sick sinus syndrome-4 (SSS4) is characterized by early and progressive sinus node and atrioventricular conduction dysfunction. Patients show bradycardia and chronotropic incompetence, and may experience syncope. Atrioventricular conduction block ranges from mild to severe, and some patients also have intermittent atrial fibrillation. Many require implantation of a pacemaker, but sudden cardiac death has not been reported (Stallmeyer et al., 2017). For a general phenotypic description and discussion of genetic heterogeneity of sick sinus syndrome, see SSS1 (608567). [from OMIM]

Infantile-onset myofibrillar myopathy-12 with cardiomyopathy (MFM12) is a severe autosomal recessive disorder affecting both skeletal and cardiac muscle tissue that is apparent in the first weeks of life. Affected infants show tremor or clonus at birth, followed by onset of rapidly progressive generalized muscle weakness and dilated cardiomyopathy and cardiac failure, usually resulting in death by 6 months of age. Skeletal and cardiac muscle tissues show hypotrophy of type I muscle fibers and evidence of myofibrillar disorganization (summary by Weterman et al., 2013). For a discussion of genetic heterogeneity of myofibrillar myopathy, see MFM1 (601419). [from OMIM]

ADCY5 dyskinesia is a hyperkinetic movement disorder (more prominent in the face and arms than the legs) characterized by infantile to late-adolescent onset of chorea, athetosis, dystonia, myoclonus, or a combination of these. To date, affected individuals have had overlapping (but not identical) manifestations with wide-ranging severity. The facial movements are typically periorbital and perioral. The dyskinesia is prone to episodic or paroxysmal exacerbation lasting minutes to hours, and may occur during sleep. Precipitating factors in some persons have included emotional stress, intercurrent illness, sneezing, or caffeine; in others, no precipitating factors have been identified. In some children, severe infantile axial hypotonia results in gross motor delays accompanied by chorea, sometimes with language delays. The overall tendency is for the abnormal movements to stabilize in early middle age, at which point they may improve in some individuals; less commonly, the abnormal movements are slowly progressive, increasing in severity and frequency. [from GeneReviews]