This is a rare heritable condition so far reported in one family in which obesity was associated with a progressive retinal degeneration (dystrophy).
Night blindness and a progressive reduction in vision are features. Examination of the retina shows a loss of pigmentation with narrowing of retinal blood vessels. Color vision testing reveals mild but nonspecific alterations in color vision. An ERG (electroretinogram) test shows a generalized malfunction of the rods and cones. Peripheral vision is more severely affected than central vision. Patients may not have symptoms until the second or third decade of life.
Obesity and an elevated body mass index (BMI) seem to be the only systemic findings in this disorder.
A gene mutation is responsible for this autosomal recessive condition. Affected individuals must have both copies of the mutation while carriers (such as parents with only one copy) are normal. Such parents can expect that 1 in 4 of their children will inherit both copies and suffer from this condition.
The diagnosis is most likely made by an eye doctor based on an eye examination. Little is known of the natural history of this condition but it likely does not impact longevity. Low vision aids may be helpful to achieve reading vision.