This syndrome has both vision and hearing problems. It is a rare congenital disorder, first reported in 1971, and only about 30 cases have been reported worldwide, many from parents who were related to each other.
The vision problems are congenital, resulting from a genetic defect in an important single cell layer of tissue on the back of the cornea known as the endothelium whose function is to maintain normal hydration of the cornea. As a result of the gene mutation, the endothelium is unable to function normally and the cornea becomes water-logged and cloudy. Vision is variable but sometimes is severely impacted by the loss of transparency, even down to being able only to discern hand motions. The associated deafness is progressive, with apparently normal hearing at birth, and becoming obviously symptomatic in the second and third decades of life.
This disorder occurs sporadically (without a family history) about half the time and the remaining cases are born to consanguineous (related) parents. It is an autosomal recessive disorder that results from a mutation in a gene located on chromosome 20. Parents have normal vision and hearing but each carries a single copy of the mutation and when offspring receive both copies, they may exhibit the signs and symptoms of this disorder.
There are many causes of corneal clouding, many of which are inherited. Only an eye doctor can determine if the condition is Harboyan syndrome but an important association necessary to the diagnosis is the presence of progressive deafness. A corneal transplant can improve vision significantly.