Exclusion of the Friedreich ataxia gene from chromosome 19.

Friedreich ataxia, a progressive neurodegenerative disorder, is an autosomal recessive disease with a carrier frequency of 1/110 in the United Kingdom. The pathophysiological basis for the disease is not known and the chromosomal location of the mutation remains unidentified. As part of an attempt to map the mutation using linked DNA markers, we demonstrate that the Friedreich ataxia gene is excluded from human chromosome 19. This study also demonstrates that the insulin receptor, which maps to chromosome 19 and may be associated with abnormal biochemical features in some patients, is not the basic defect.