VISUAL PIGMENT GENE CHANGES IN ADRENOLEUKODYSTROPHY

Purpose. The gene for X-linked adrenoleukodystrophy, a neurodegenerati ve disorder, is closely linked to the red/green color pigment genes on the distal X-chromosome Xq28 and one kindred is known to have a genet ic change affecting both loci. The purpose of this article is to perfo rm a systematic assessment of the frequency of this situation in many affected kindreds. Methods. Recombinant DNA probes were used in blot h ybridization studies to determine the structure of the color pigment g enes in affected males from 59 different adrenoleukodystrophy kindreds . Whenever possible, color vision was measured using the Farnsworth 10 0-Hue test. Results. Eleven of the 59 kindreds had abnormal color pigm ent gene clusters; these included fusion genes and changes in gene num ber. Only one kindred had a deletion of sequences immediately 5' to th e color pigment genes. Conclusions. The incidence of color pigment gen e changes in our 59 adrenoleukodystrophy kindreds is approximately twi ce the frequency of defective color vision reported in historic studie s but is about the same as that found in studies of the actual genes i n large populations. However, the range of changes in the color pigmen t genes in adrenoleukodystrophy is broader than encountered in most po pulations. Changes in the highly conserved color pigment genes reflect reorganizations in the Xq28 chromosomal region, some of which involve the contiguous gene for adrenoleukodystrophy.