Linkage heterogeneity between X-linked retinitis pigmentosa and a map of 10 RFLP loci.

In nine families in which X-linked retinitis pigmentosa (XLRP) is segregating, the lod scores of XLRP in a map of 10 RFLP loci were obtained by multipoint linkage analysis. The XLRP locus was located telomeric to DXS7 in seven of the families and centromeric to DXS7 in two of the families. Under the hypothesis of two XLRP loci, a heterogeneity (admixture) test was performed, providing significant evidence of heterogeneity in XLRP (P less than .01). No correlation was detected between the clinical manifestations of XLRP and the two different disease loci.