X-linked intellectual disability, Najm type

Alternate names

X-linked intellectual disability - microcephaly - pontocerebellar hypoplasia; MICPCH; Intellectual disability and microcephaly with pontine and cerebellar hypoplasia ; MICPCH SYNDROME; microcephaly with pontine and cerebellar hypoplasia ; X-linked intellectual disability-microcephaly-pontocerebellar hypoplasia syndrome

Definition

Najm type X-linked intellectual deficit is a rare cerebellar dysgenesis syndrome characterized by variable clinical manifestations ranging from mild intellectual deficit with or without congenital nystagmus, to severe cognitive impairment associated with cerebellar and pontine hypoplasia/atrophy and abnormalities of cortical development.

Epidemiology

Prevalence of this rare neurological syndrome is unknown. Up to 35 families have been reported to date.

Cause

Point mutations and deletions in the CASK gene (Xp11.4) have been found in patients with this syndrome.

Inheritance

X-linked dominant inheritance

Transmission follows an X-linked dominant pattern.

Signs and symptoms

• Patients (mostly females) have been reported to have variable clinical manifestations including intellectual deficit, severe developmental delay, seizures, unsteady gait, sensorineural hearing loss and postnatal microcephaly (in most cases).
• Minor facial anomalies include: low or broad forehead, hypertelorism, long philtrum and micrognathia.
• Ocular findings are also variable and include congenital nystagmus, strabismus, cataracts, myopia or
• reduced visual acuity.
• Males appear to be more severely affected.

Clinical presentation

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed.

80%-99% of people have these symptoms

• Cerebellar hypoplasia(Small cerebellum)
• Intellectual disability, moderate(IQ between 34 and 49)
• Severe global developmental delay

30%-79% of people have these symptoms

• Broad forehead(Increased width of the forehead)
• Cataract(Clouding of the lens of the eye)
• Cerebral cortical atrophy(Decrease in size of the outer layer of the brain due to loss of brain cells)
• Gait disturbance(Abnormal gait)
• [[Hypertelorism](Wide-set eyes)
• Long philtrum
• Macrotia(Large ears)
• Microcephaly(Abnormally small skull)
• Micrognathia(Little lower jaw)
• Myopia(Close sighted)
• Nystagmus(Involuntary, rapid, rhythmic eye movements)
• Seizure
• Sensorineural hearing impairment
• Strabismus(Cross-eyed)
• Visual impairment(Impaired vision)
• Wide nasal bridge(Broad nasal bridge)

Diagnosis

• Magnetic resonance imaging (MRI) generally shows pontocerebellar hypoplasia/atrophy and simplified cortical gyri.
• Molecular genetic testing is needed to confirm diagnosis.

NIH genetic and rare disease info

• NIH info on X-linked intellectual disability, Najm type

X-linked intellectual disability, Najm type is a rare disease.

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