Two McLeod patients with novel mutations in XK.

McLeod syndrome (MLS) is a rare, X-linked, late-onset, disease involving hematological, brain, and neuromuscular systems, caused by mutations in XK that result in either defective XK or complete loss of XK protein. Acanthocytosis of erythrocytes is a typical feature. We report novel mutations in two patients who exhibited typical clinical characteristics of MLS. The coding and flanking intronic regions of XK were amplified by PCR, sequenced, and compared with the normal XK sequence. XK protein, and its complexed partner protein, Kell, were assessed by Western blot analysis. Patient 1 was found to have a single base insertion, 605insA at 175Ile creating a frame shift within the coding sequence of XK. Patient 2 had a single base substitution in the 3' splice sequence of intron 2 (IVS2-2a>g). In both cases mutations resulted in the absence of XK protein.