Cerebellar Atrophy, Visual Impairment, and Psychomotor Retardation
Patient Information
Characteristics
Background and History
This is a heritable condition with severe neurological deficits and visual impairment described so far described in several families of European and middle eastern origins.
Clinical Correlations
Infants are usually born with small heads (microcephaly). They experience physical and mental developmental delays and those who learn to speak do so late. Visual impairment may be due to abnormal brain connections although one patient had evidence of optic nerve degeneration (atrophy). There are purposeless movements (dystonia) in the limbs of some individuals. Muscles in the trunk are weak and scoliosis can develop. The muscle tone in the limbs is often increased. The gums in the mouth often appear enlarged (gingival hyperplasia) while the lower jaw is shortened.
MRIs of the brain reveal degeneration and there is a lack of normal development of some structures.
Genetics
Inheritance
This is an autosomal recessive condition in which both members of a specific pair of genes are changed (mutated). The parents each have one copy of the mutation and are clinically normal. When both parents carry one such copy they confer a 25% risk to each of their children to inherit the two mutations.
Pedigree
Autosomal recessive
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
Diagnosis and Prognosis
Pediatricians, ophthalmologists, and neurologists are likely to collaborate in the diagnosis and care of these patients. No treatment has been reported although physical therapy and visual stimulation may be helpful.
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