Etiology of vision loss in ganglioside GM3 synthase deficiency.

PURPOSE: To investigate the cause of vision loss in patients with ganglioside GM3 synthase deficiency, a newly described rare autosomal recessive infantile-onset symptomatic epilepsy syndrome associated with developmental stagnation and blindness.

METHODS

We examined four children from two related Amish sibships. Molecular genetic analysis confirmed inheritance of the founder mutation. Electroretinography and fundus photography were obtained in two patients.

RESULTS

Despite an initial suspicion of retinal degeneration, retinal function was found to be preserved in both patients and ERG amplitudes were within normal limits. Ophthalmoscopy showed bilateral optic atrophy in all patients.

CONCLUSIONS

Vision loss in GM3 synthase deficiency results from central nervous system and optic nerve involvement. Retinal function appears to be otherwise normal into the teenage years.