Dandy-Walker syndrome- MedGen UID:
- 4150
- •Concept ID:
- C0010964
- •
- Disease or Syndrome
Dandy-Walker malformation (DWM) 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).
Azorean disease- MedGen UID:
- 9841
- •Concept ID:
- C0024408
- •
- Disease or Syndrome
Spinocerebellar ataxia type 3 (SCA3), also known as Machado-Joseph disease (MJD), is characterized by progressive cerebellar ataxia and variable findings including pyramidal signs, a dystonic-rigid extrapyramidal syndrome, significant peripheral amyotrophy and generalized areflexia, progressive external ophthalmoplegia, action-induced facial and lingual fasciculations, and bulging eyes. Neurologic findings tend to evolve as the disorder progresses.
PMM2-congenital disorder of glycosylation- MedGen UID:
- 138111
- •Concept ID:
- C0349653
- •
- Disease or Syndrome
PMM2-CDG, the most common of a group of disorders of abnormal glycosylation of N-linked oligosaccharides, is divided into three clinical stages: infantile multisystem, late-infantile and childhood ataxia–intellectual disability, and adult stable disability. The clinical manifestations and course are highly variable, ranging from infants who die in the first year of life to mildly affected adults. Clinical findings tend to be similar in sibs. In the infantile multisystem presentation, infants show axial hypotonia, hyporeflexia, esotropia, and developmental delay. Feeding problems, vomiting, faltering growth, and developmental delay are frequently seen. Subcutaneous fat may be excessive over the buttocks and suprapubic region. Two distinct clinical courses are observed: (1) a nonfatal neurologic course with faltering growth, strabismus, developmental delay, cerebellar hypoplasia, and hepatopathy in infancy followed by neuropathy and retinitis pigmentosa in the first or second decade; and (2) a more severe neurologic-multivisceral course with approximately 20% mortality in the first year of life. The late-infantile and childhood ataxia–intellectual disability stage, which begins between ages three and ten years, is characterized by hypotonia, ataxia, severely delayed language and motor development, inability to walk, and IQ of 40 to 70; other findings include seizures, stroke-like episodes or transient unilateral loss of function, coagulopathy, retinitis pigmentosa, joint contractures, and skeletal deformities. In the adult stable disability stage, intellectual ability is stable; peripheral neuropathy is variable, progressive retinitis pigmentosa and myopia are seen, thoracic and spinal deformities with osteoporosis worsen, and premature aging is observed; females may lack secondary sexual development and males may exhibit decreased testicular volume. Hypogonadotropic hypogonadism and coagulopathy may occur. The risk for deep venous thrombosis is increased.
Spinocerebellar ataxia type 1- MedGen UID:
- 155703
- •Concept ID:
- C0752120
- •
- Disease or Syndrome
Spinocerebellar ataxia type 1 (SCA1) is characterized by progressive cerebellar ataxia, dysarthria, and eventual deterioration of bulbar functions. Early in the disease, affected individuals may have gait disturbance, slurred speech, difficulty with balance, brisk deep tendon reflexes, hypermetric saccades, nystagmus, and mild dysphagia. Later signs include slowing of saccadic velocity, development of up-gaze palsy, dysmetria, dysdiadochokinesia, and hypotonia. In advanced stages, muscle atrophy, decreased deep tendon reflexes, loss of proprioception, cognitive impairment (e.g., frontal executive dysfunction, impaired verbal memory), chorea, dystonia, and bulbar dysfunction are seen. Onset is typically in the third or fourth decade, although childhood onset and late-adult onset have been reported. Those with onset after age 60 years may manifest a pure cerebellar phenotype. Interval from onset to death varies from ten to 30 years; individuals with juvenile onset show more rapid progression and more severe disease. Anticipation is observed. An axonal sensory neuropathy detected by electrophysiologic testing is common; brain imaging typically shows cerebellar and brain stem atrophy.
Spinocerebellar ataxia type 2- MedGen UID:
- 155704
- •Concept ID:
- C0752121
- •
- Disease or Syndrome
Spinocerebellar ataxia type 2 (SCA2) is characterized by progressive cerebellar ataxia, including nystagmus, slow saccadic eye movements, and in some individuals, ophthalmoparesis or parkinsonism. Pyramidal findings are present; deep tendon reflexes are brisk early on and absent later in the course. Age of onset is typically in the fourth decade with a ten- to 15-year disease duration.
Joubert syndrome 6- MedGen UID:
- 342805
- •Concept ID:
- C1853153
- •
- Disease or Syndrome
Classic Joubert syndrome (JS) is characterized by three primary findings: A distinctive cerebellar and brain stem malformation called the molar tooth sign (MTS). Hypotonia. Developmental delays. Often these findings are accompanied by episodic tachypnea or apnea and/or atypical eye movements. In general, the breathing abnormalities improve with age, truncal ataxia develops over time, and acquisition of gross motor milestones is delayed. Cognitive abilities are variable, ranging from severe intellectual disability to normal. Additional findings can include retinal dystrophy, renal disease, ocular colobomas, occipital encephalocele, hepatic fibrosis, polydactyly, oral hamartomas, and endocrine abnormalities. Both intra- and interfamilial variation are seen.
Joubert syndrome with oculorenal defect- MedGen UID:
- 340930
- •Concept ID:
- C1855675
- •
- Disease or Syndrome
Classic Joubert syndrome (JS) is characterized by three primary findings: A distinctive cerebellar and brain stem malformation called the molar tooth sign (MTS). Hypotonia. Developmental delays. Often these findings are accompanied by episodic tachypnea or apnea and/or atypical eye movements. In general, the breathing abnormalities improve with age, truncal ataxia develops over time, and acquisition of gross motor milestones is delayed. Cognitive abilities are variable, ranging from severe intellectual disability to normal. Additional findings can include retinal dystrophy, renal disease, ocular colobomas, occipital encephalocele, hepatic fibrosis, polydactyly, oral hamartomas, and endocrine abnormalities. Both intra- and interfamilial variation are seen.
Dandy-Walker malformation-postaxial polydactyly syndrome- MedGen UID:
- 341751
- •Concept ID:
- C1857351
- •
- Disease or Syndrome
A syndromic disorder with the association between Dandy-Walker malformation and postaxial polydactyly as a major feature. The Dandy-Walker malformation has a variable expression and characteristics of a posterior fossa cyst communicating with the fourth ventricle, the partial or complete absence of the cerebellar vermis, and facultative hydrocephalus. Postaxial polydactyly includes tetramelic postaxial polydactyly of hands and feet with possible enlargement of the fifth metacarpal and metatarsal bones, as well as bifid fifth metacarpals.
Autosomal recessive spinocerebellar ataxia 2- MedGen UID:
- 349134
- •Concept ID:
- C1859298
- •
- Disease or Syndrome
Autosomal recessive spinocerebellar ataxia-2 (SCAR2) is a neurologic disorder characterized by onset of impaired motor development and ataxic gait in early childhood. Additional features often include loss of fine motor skills, dysarthria, nystagmus, cerebellar signs, and delayed cognitive development with intellectual disability. Brain imaging shows cerebellar atrophy. Overall, the disorder is non- or slowly progressive, with survival into adulthood (summary by Jobling et al., 2015).
Syndromic X-linked intellectual disability Najm type- MedGen UID:
- 437070
- •Concept ID:
- C2677903
- •
- Disease or Syndrome
CASK disorders include a spectrum of phenotypes in both females and males. Two main types of clinical presentation are seen: Microcephaly with pontine and cerebellar hypoplasia (MICPCH), generally associated with pathogenic loss-of-function variants in CASK. X-linked intellectual disability (XLID) with or without nystagmus, generally associated with hypomorphic CASK pathogenic variants. MICPCH is typically seen in females with moderate-to-severe intellectual disability, progressive microcephaly with or without ophthalmologic anomalies, and sensorineural hearing loss. Most are able to sit independently; 20%-25% attain the ability to walk; language is nearly absent in most. Neurologic features may include axial hypotonia, hypertonia/spasticity of the extremities, and dystonia or other movement disorders. Nearly 40% have seizures by age ten years. Behaviors may include sleep disturbances, hand stereotypies, and self biting. MICPCH in males may occur with or without severe epileptic encephalopathy in addition to severe-to-profound developmental delay. When seizures are present they occur early and may be intractable. In individuals and families with milder (i.e., hypomorphic) pathogenic variants, the clinical phenotype is usually that of XLID with or without nystagmus and additional clinical features. Males have mild-to-severe intellectual disability, with or without nystagmus and other ocular features. Females typically have normal intelligence with some displaying mild-to-severe intellectual disability with or without ocular features.
Intellectual disability, autosomal dominant 20- MedGen UID:
- 462050
- •Concept ID:
- C3150700
- •
- Disease or Syndrome
Neurodevelopmental disorder with hypotonia, stereotypic hand movements, and impaired language (NEDHSIL) is characterized by global developmental delay with hypotonia, poor motor development with limited walking, impaired intellectual development with poor or absent speech, and behavioral abnormalities. Almost all affected individuals demonstrate repetitive stereotypic hand movements that can be categorized as hyperkinetic and resembling those of Rett syndrome (RTT; 312750). About 80% of patients develop various types of seizures that may be refractory to treatment. Additional features may include dysmorphic facial features, particularly dysplastic ears, poor eye contact, episodic hyperventilation, tendency to infection, and abnormalities on brain imaging, such as enlarged ventricles, thin corpus callosum, and delayed myelination (summary by Vrecar et al., 2017, Paciorkowski et al., 2013).
Meckel syndrome, type 10- MedGen UID:
- 481666
- •Concept ID:
- C3280036
- •
- Disease or Syndrome
Meckel syndrome is a disorder with severe signs and symptoms that affect many parts of the body. The most common features are enlarged kidneys with numerous fluid-filled cysts; an occipital encephalocele, which is a sac-like protrusion of the brain through an opening at the back of the skull; and the presence of extra fingers and toes (polydactyly). Most affected individuals also have a buildup of scar tissue (fibrosis) in the liver.\n\nOther signs and symptoms of Meckel syndrome vary widely among affected individuals. Numerous abnormalities of the brain and spinal cord (central nervous system) have been reported in people with Meckel syndrome, including a group of birth defects known as neural tube defects. These defects occur when a structure called the neural tube, a layer of cells that ultimately develops into the brain and spinal cord, fails to close completely during the first few weeks of embryonic development. Meckel syndrome can also cause problems with development of the eyes and other facial features, heart, bones, urinary system, and genitalia.\n\nBecause of their serious health problems, most individuals with Meckel syndrome die before or shortly after birth. Most often, affected infants die of respiratory problems or kidney failure.
Autosomal recessive spinocerebellar ataxia 13- MedGen UID:
- 766730
- •Concept ID:
- C3553816
- •
- Disease or Syndrome
Autosomal recessive spinocerebellar ataxia-13 (SCAR13) is an autosomal recessive neurologic disorder characterized by delayed psychomotor development beginning in infancy. Affected individuals show mildly to profoundly impaired intellectual development with poor or absent speech as well as gait and stance ataxia and hyperreflexia. Most individuals also have eye movement abnormalities. Brain MRI shows cerebellar atrophy and ventriculomegaly (Guergueltcheva et al., 2012).
Meckel syndrome, type 1- MedGen UID:
- 811346
- •Concept ID:
- C3714506
- •
- Disease or Syndrome
Meckel syndrome, also known as Meckel-Gruber syndrome, is a severe pleiotropic autosomal recessive developmental disorder caused by dysfunction of primary cilia during early embryogenesis. There is extensive clinical variability and controversy as to the minimum diagnostic criteria. Early reports, including that of Opitz and Howe (1969) and Wright et al. (1994), stated that the classic triad of Meckel syndrome comprises (1) cystic renal disease; (2) a central nervous system malformation, most commonly occipital encephalocele; and (3) polydactyly, most often postaxial. However, based on a study of 67 patients, Salonen (1984) concluded that the minimum diagnostic criteria are (1) cystic renal disease; (2) CNS malformation, and (3) hepatic abnormalities, including portal fibrosis or ductal proliferation. In a review of Meckel syndrome, Logan et al. (2011) stated that the classic triad first described by Meckel (1822) included occipital encephalocele, cystic kidneys, and fibrotic changes to the liver.
Genetic Heterogeneity of Meckel Syndrome
See also MKS2 (603194), caused by mutation in the TMEM216 gene (613277) on chromosome 11q12; MKS3 (607361), caused by mutation in the TMEM67 gene (609884) on chromosome 8q; MKS4 (611134), caused by mutation in the CEP290 gene (610142) on chromosome 12q; MKS5 (611561), caused by mutation in the RPGRIP1L gene (610937) on chromosome 16q12; MKS6 (612284), caused by mutation in the CC2D2A gene (612013) on chromosome 4p15; MKS7 (267010), caused by mutation in the NPHP3 (608002) gene on chromosome 3q22; MKS8 (613885), caused by mutation in the TCTN2 gene (613846) on chromosome 12q24; MKS9 (614209), caused by mutation in the B9D1 gene (614144) on chromosome 17p11; MKS10 (614175), caused by mutation in the B9D2 gene (611951) on chromosome 19q13; MKS11 (615397), caused by mutation in the TMEM231 gene (614949) on chromosome 16q23; MKS12 (616258), caused by mutation in the KIF14 gene (611279) on chromosome 1q32; MKS13 (617562), caused by mutation in the TMEM107 gene (616183) on chromosome 17p13; and MKS14 (619879), caused by mutation in the TXNDC15 gene (617778) on chromosome 5q31.
Congenital microcephaly - severe encephalopathy - progressive cerebral atrophy syndrome- MedGen UID:
- 816301
- •Concept ID:
- C3809971
- •
- Disease or Syndrome
Asparagine synthetase deficiency (ASD) mainly presents as a triad of congenital microcephaly, severe developmental delay, and axial hypotonia followed by spastic quadriplegia. Low cerebrospinal fluid (CSF) asparagine level can help the clinician in differentiating this disorder from others. In most cases age of onset of apnea, excessive irritability, and seizures is soon after birth. Affected individuals typically do not acquire any developmental milestones. Spastic quadriplegia can lead to severe contractures of the limbs and neurogenic scoliosis. Feeding difficulties (gastroesophageal reflux disease, frequent vomiting, swallowing dysfunction, and gastroesophageal incoordination) are a significant problem in most affected individuals. A majority have cortical blindness. MRI findings are nonspecific but may include generalized atrophy and simplified gyral pattern.
Complex cortical dysplasia with other brain malformations 6- MedGen UID:
- 862720
- •Concept ID:
- C4014283
- •
- Disease or Syndrome
Any complex cortical dysplasia with other brain malformations in which the cause of the disease is a mutation in the TUBB gene.
Ataxia - intellectual disability - oculomotor apraxia - cerebellar cysts syndrome- MedGen UID:
- 863258
- •Concept ID:
- C4014821
- •
- Disease or Syndrome
Poretti-Boltshauser syndrome is an autosomal recessive disorder characterized by cerebellar dysplasia, cerebellar vermis hypoplasia, cerebellar cysts in most patients, high myopia, variable retinal dystrophy, and eye movement abnormalities. Affected individuals have delayed motor development and often have speech delay. Cognitive function can range from normal to intellectually disabled (summary by Aldinger et al., 2014).
Intellectual disability, autosomal dominant 48- MedGen UID:
- 1619532
- •Concept ID:
- C4540321
- •
- Mental or Behavioral Dysfunction
A rare genetic multiple congenital anomalies/dysmorphic syndrome characterized by global developmental delay and moderate to severe intellectual disability, as well as variable other manifestations, such as macro- or microcephaly, epilepsy, hypotonia, behavioral problems, stereotypic movements, and facial dysmorphism (including arched eyebrows, long palpebral fissures, prominent nasal bridge, upturned nose, dysplastic ears, and broad mouth), among others. Brain imaging may show cerebellar anomalies, hypoplastic corpus callosum, enlarged ventricles, polymicrogyria, or white matter abnormalities.
Mitochondrial complex 4 deficiency, nuclear type 11- MedGen UID:
- 1760275
- •Concept ID:
- C5436694
- •
- Disease or Syndrome
Mitochondrial complex IV deficiency nuclear type 11 (MC4DN11) is an autosomal recessive metabolic disorder characterized by a childhood-onset sensory neuronopathy and additional features which may include hypotonia, cerebellar ataxia, tremor, dystonia, choreoathetosis, and/or dysarthria. Patients may have variable motor delay, speech delay, or impaired intellectual development (summary by Doss et al., 2014; Otero et al., 2019; Xu et al., 2019; Dong et al., 2021).
For a discussion of genetic heterogeneity of mitochondrial complex IV (cytochrome c oxidase) deficiency, see 220110.
Neurodevelopmental disorder with dysmorphic facies and cerebellar hypoplasia- MedGen UID:
- 1786150
- •Concept ID:
- C5543332
- •
- Disease or Syndrome
Neurodevelopmental disorder with dysmorphic facies and cerebellar hypoplasia (NEDFACH) is an autosomal recessive disorder characterized by global developmental delay and intellectual disability. The phenotype is variable: more severely affected individuals have poor overall growth with microcephaly, delayed walking, spasticity, and poor or absent speech, whereas others may achieve more significant developmental milestones and even attend special schooling. Brain imaging shows abnormalities of the cerebellum, most commonly cerebellar hypoplasia, although other features, such as thin corpus callosum and delayed myelination, may also be present. Dysmorphic facial features include sloping forehead, upslanting palpebral fissures, and hypertelorism. Additional more variable manifestations may include cardiac ventricular septal defect, spasticity, cataracts, optic nerve hypoplasia, seizures, and joint contractures (summary by Van Bergen et al., 2020).
Zaki syndrome- MedGen UID:
- 1794247
- •Concept ID:
- C5562037
- •
- Disease or Syndrome
Zaki syndrome (ZKS) is characterized by developmental delay, progressive microcephaly, and short stature, as well as dysmorphic features including sparse scalp hair, cupped ears, wide nose and mouth, short philtrum, and high-arched palate. Other variable features have been observed, including ocular, skeletal, cardiac, and renal anomalies (Chai et al., 2021).
Neurocardiofaciodigital syndrome- MedGen UID:
- 1804193
- •Concept ID:
- C5677020
- •
- Disease or Syndrome
Neurocardiofaciodigital syndrome (NCFD) is characterized by severe developmental delay, variable brain anomalies, congenital heart defects, dysmorphic facial features, and a distinctive type of synpolydactyly with a supernumerary hypoplastic digit between the fourth and fifth digits of the hands and/or feet. Other features include eye abnormalities, hearing impairment, and electroencephalogram anomalies (summary by Horn et al., 2021).
Spinocerebellar ataxia, autosomal recessive 33- MedGen UID:
- 1824070
- •Concept ID:
- C5774297
- •
- Disease or Syndrome
Autosomal recessive spinocerebellar ataxia-33 (SCAR33) is a neurologic disorder characterized by delayed motor development apparent in infancy, unsteady ataxic gait, intention tremor, nystagmus, and speech delay with dysarthria. Some patients have seizures and/or learning difficulties. Brain imaging shows cerebellar hypoplasia (Elsaid et al., 2017).
Neurodevelopmental disorder with motor and language delay, ocular defects, and brain abnormalities- MedGen UID:
- 1841232
- •Concept ID:
- C5830596
- •
- Disease or Syndrome
Neurodevelopmental disorder with motor and language delay, ocular defects, and brain abnormalities (NEDMLOB) is an autosomal recessive neurologic disorder characterized by the onset of features in infancy or early childhood. Affected individuals show hypotonia, severe motor delay with ataxic gait or sometimes an inability to achieve walking, and impaired intellectual development with speech and language delay. Ocular defects can include optic atrophy, nystagmus, strabismus, and retinal dystrophy. Additional features may include seizures (in some), dysmorphic facial features, poor overall growth, and variable brain imaging abnormalities (Tepe et al., 2023).
Ciliary dyskinesia, primary, 53- MedGen UID:
- 1851509
- •Concept ID:
- C5882728
- •
- Disease or Syndrome
Primary ciliary dyskinesia-53 (CILD53) is an autosomal recessive disorder characterized by randomization of the left-right body asymmetry and respiratory symptoms (Hjeij et al., 2023).
For a discussion of genetic heterogeneity of primary ciliary dyskinesia, see CILD1 (244400).