Summary
Optic atrophies (OA) refer to a specific group of hereditary optic neuropathies in which the cause of the optic nerve dysfunction is inherited either in an autosomal dominant or autosomal recessive pattern. Autosomal dominant optic atrophy (ADOA), type Kjer, is the most common OA, whereas autosomal recessive optic atrophy (AROA) is a rare form. Prevalence of ADOA ranges from 1:50,000 to 1:10,000. The frequency of AROA is unknown but the disease seems rare. The age at onset of ADOA is usually between 4 and 6 years, although visual symptoms are usually imperceptible until late in life due to the slowly progressive decrease in visual acuity. MRI of patients with ADOA reflects the important loss of tissue of the optic nerve due to a dramatic reduction of the retinal ganglion cells. There is no neurological deficit. But, a mild hearing loss may be encountered. In the pure congenital AROA, visual impairment is severe. This AROA is never associated with neurological disorder. Since the visual symptoms are important, AROA can be discovered very early, usually before the age of 4 years. In many families, mutations of the OPA1 gene account for ADOA. OPA1 maps to chromosome 3q28 and encodes for an homologue of yeast dynamin-related GTPase. More than 60 mutations in the OPA1 gene have been associated with ADOA. This protein is ubiquitously expressed in retinal ganglion cells and optic nerve. Two other ADOA locus have been described :on chromosome 18q12.2-q12.3 (OPA4) and on chromosome 22q12.1-q13.1 (OPA5). A locus for isolated AROA maps to chromosome 8q21-q22 (ROA1). *Author: Dr C. Orssaud (March 2005)*.
