ANALYSIS IN A LARGE SPANISH FAMILY WITH X-LINKED RETINITIS-PIGMENTOSA- PHENOTYPE-GENOTYPE CORRELATION

X-linked retinitis pigmentosa (XLRP) accounts for 10-25% of RP familie s and causes the most severe form of the disease in terms of onset and progression. Although three different loci (RP3, RP2 and RP15) have b een proposed on the short arm of the X-chromosome by linkage analysis, RP3 represents the disease locus in the majority of XLRP families. Th e identification of female carriers of X-linked RP is important for ge netic counselling. The presence of fundus and electroretinogram (ERG) abnormalities have been reported to be as high as 87 and 90%, respecti vely. However, in clinical practice it has not always been possible to know the carrier state of females at risk. Thirty-five members of a S panish family with X-linked RP were evaluated by linkage analysis usin g nine polymorphic markers (CYBB, DXS1110 M6, DXS6679, DXS1068, DXS105 8, MAOA, MAOB and DXS6849) that map to the X-chromosome region Xp21.1 to Xp11.3, in an attempt to determine the carrier state of these femal es at risk. It was possible to establish that a RP3 mutation is, most likely, segregating in this family. (C) Munksgaard, 1998.