A linkage analysis has been performed on three Australian families segregating for autosomal dominant retinitis pigmentosa (ADRP). No evidence of linkage has been found in any of the pedigrees studied between the locus D3S47 and the gene for ADRP. The D3S47 locus was found to show very close linkage with the ADRP gene in a large Irish pedigree. Our study together with a similar report on a British family indicates that there is genetic heterogeneity in this disease.

Linkage analysis has been performed on a large Australian family segregating for the autosomal dominant form of retinitis pigmentosa (ADRP). The majority of patients had no subjective symptoms of night blindness until their second decade and good visual acuity until late in life. The disease in this family has been classified as Type II ADRP according to the subdivisions provided by both Massof and Finkelstein and Fishman and colleagues. Linkage (Omax:0.08 at Zmax:4.78) is here demonstrated between the disease locus and D3S47 (a marker locus on the long arm of chromosome 3), which showed in an earlier study very close linkage without recombination to the disease locus in an Irish pedigree with a clinically more severe and early onset (Type I) ADRP.