Analysis of deletions in three McLeod patients: exclusion of the XS locus from the Xp21.1-Xp21.2 region

The McLeod syndrome is a rare X-linked recessive disorder characterized by blood group, neuromuscular and haematopoietic abnormalities. It is caused b y XK gene defects and may include large deletions in the Xp21 region. Analy sis of three unrelated McLeod patients for the presence of the XK, DMD, CYB B, ETX1, RPGR and OTC loci, as well as for the DXS709 marker, revealed dele tions from the 39th exon of DMD to the ETX1 locus (patient Be), from the XK to RPGR loci (patient Bi) and from the XK to CYBB loci (patient Lh). All t hree patients normally expressed the Lutheran (Lu) red cell antigens, thus excluding the interval between the RPGR and DMD genes as site of the XS loc us, previously mapped to the Xp21.2-Xq21.1 region and thought to regulate t he expression of the LU blood group gene on chromosome 19.