Cataracts, Congenital, and Hypomyelinating Leukodystrophy
Patient Information
Characteristics
Background and History
This is a recently described disorder of congenital cataracts and progressive neurological disease.
Clinical Correlations
Infants and young children usually have cataracts but otherwise appear normal at birth. Developmental delays become apparent sometime in the first year of life. Walking is late in onset and most children require some assistance from the beginning. General weakness and muscle wasting soon become apparent and many patients require a wheelchair later in the first decade of life. Instability (ataxia), tremors, slurred speech, and spasticity are also evident during this period. A few patients have had seizures but this is not a prominent feature. The neurologic signs gradually worsen. Cognitive impairment ranges from mild to moderate.
Genetics
Inheritance
This is an autosomal recessive disorder in which the condition is only manifest in individuals who inherit both mutant genes. The parents each carry one mutation and therefore each of their children has a one in four chance of inheriting this condition.
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
Lifespan is variable with some children not surviving beyond the age of 12 years and at least one lived to adulthood. An ophthalmologic examination reveals the cataracts early but the neurologic signs appear later and the diagnosis is likely made by a neurologist. Cataracts can be surgically removed but no treatment is available for the neurologic deterioration. Physical therapy and special education can be helpful, however.
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