Dominant optic atrophy, type Kjer, is an autosomal dominant eye disease that is characterized by progressive optic atrophy with onset in early childhood, decrease of visual acuity, colour vision defects and centrocecal scotoma. By examination of 5 Danish families and the use of polymorphic markers, we have refined the localization of the OPA1 locus and assigned it to a 1.4-cM interval on chromosome 3q28-3q29, between markers D3S3669 and D3S3562. This localizes the gene on a 3-Mb YAC contig covering the disease locus. We have also located a possible candidate gene HRY to this contig.