Best's vitelliform macular dystrophy (Best's disease) is an autosomal dominant disorder of unknown causes and is typically characterised by an accumulation of lipofuscin-like material in the subretinal space of the macula. The disease gene has been localised to chromosome 11q12-13.1 within a 1.4 Mbp interval flanked by markers at D11S1765 and uteroglobin (UGB). Here we report the refined mapping of the gene encoding the p127 kDa subunit (DDB1) of a UV damage-specific DNA binding protein within the D11S1765-UGB region. Northern blot analysis demonstrates an abundant expression of the DDB1 transcript in the retina suggesting a functional role for DDB1 in this tissue. These considerations together with the chromosomal localisation have led us to evaluate the possible involvement of DDB1 in the pathogenesis of Best's disease.