Hypotrichosis with Juvenile Macular Degeneration
Patient Information
Characteristics
Background and History
This is a rare disorder first reported in the second half of the 20th century.
Clinical Correlations
Loss of scalp hair begins at about 3 months of age although there may be some regrowth during puberty. Body hair elsewhere seems to be normal including the eyebrows and eyelashes. The retina, the light sensing tissue in the back of the eye, is also abnormal and its rods and cones gradually deteriorate with age. Vision loss begins in the first decade of life and progresses in many individuals to blindness.
Genetics
Inheritance
This disorder is transmitted in an autosomal recessive pattern. Parents, who are unaffected, carry gene mutations which both have to transmit to their children before the disease is apparent. Such parents have a 25% risk for each of their children to inherit 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
No treatment is available to cure this disease. Low vision aids can be helpful, at least in most patients and at least for a period of time. Ophthalmologists and dermatologists usually collaborate on the diagnosis. There is no evidence for a shortening of lifespan and most individuals are otherwise healthy.
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