Still no evidence for heterogeneity in Best's vitelliform macular dystrophy.

In the November 1995 issue of the Journal, Mansergh et all suggest that there is genetic heterogeneity in the autosomal dominant eye disorder Best's vitelliform macular dystrophy (BMD) previously mapped to 1 1q13 (MIM 153700)."-' They analysed markers from chromosome 11 in two families, BTMD1 of Irish origin and Fam E of German origin. The conclusion was that the gene previously mapped to 11 qi 3 does not cause Best's disease in the German Fam E family. However, all the markers included in the study, except for PYGM, lie on the centromeric side of the BMD gene.45 In table 1 of the paper, the two point lod scores for these markers are shown and Fam E was not analysed for PYGM. In the multipoint analyses, illustrated in fig 3, the data have been calculated assuming four different penetrances but they have failed to include a single marker on the telomeric side of the gene. Not surprisingly then, Fam E show lod scores below -2, the criterion used for exclusion of linkage. The authors thus arrive at the incorrect conclusion ofexcluding linkage to the BMD region, without including the BMD region in their analyses. In our opinion there is still no evidence of genetic heterogeneity in Best's macular dystrophy and