SEVERE MANIFESTATIONS IN CARRIER FEMALES IN X-LINKED RETINITIS-PIGMENTOSA

Retinitis pigmentosa (RP) is a group of progressive hereditary disorde rs of the retina in which various modes of inheritance have been descr ibed. Here, we report on X linked RP in nine families with constant an d severe expression in carrier females. In our series. however, the ph enotype was milder and delayed in carrier females compared to hemizygo us males. This form of X linked RP could be regarded therefore as part ially dominant. The disease gene maps to chromosome Xp2.1 in the genet ic interval encompassing the RP3 locus (Zmax=13.71 at the DXS1110 locu s). Single strand conformation polymorphism and direct sequence analys is of the retinitis pigmentosa GTPase regulator (RPGR) gene, which acc ounts for RP3, failed to detect any mutation in our families. Future a dvances in the identification of X linked RP genes will hopefully help to elucidate the molecular basis of this X linked dominant RP.