Linkage studies of the Wiskott-Aldrich syndrome: polymorphisms at TIMP and the X chromosome centromere are informative markers for genetic prediction.

Eleven families segregating for the X-linked recessive immune deficiency disorder, Wiskott-Aldrich syndrome (WAS), were studied by linkage analysis with an alpha satellite DNA probe, pBamX-7, which detects polymorphisms at the X chromosome centromere, locus DXZ1, as well as three other polymorphic markers defining loci on the proximal short arm of the X chromosome. Linkage has been established between WAS and DXZ1 (zeta (theta) = 7.08 at theta = 0.03) and WAS and the TIMP gene locus (zeta (theta) = 5.09 at theta = 0.0). We have also confirmed close linkage between DXZ1 and two marker loci, DXS14 and DXS7, previously shown to be linked to the WAS locus. The probe pBamX-7 detected allelic variation in all females tested, reflecting the high frequency of polymorphism at the centromere. One WAS carrier revealed a recombination between WAS and both marker loci DXZ1 and DXS14, indicating that WAS does not map between these loci. In conjunction with previous data from genetic mapping studies of WAS, these results confirm the pericentromeric Xp localization of WAS and demonstrate the usefulness of alpha satellite DNA probes as tools for genetic prediction in WAS as well as other pericentric X-linked diseases.