Close linkage of PUM and SPTA within chromosome band 1q21.

Nine families were examined for linkage on chromosome 1 between the hypervariable gene PUM and the alpha-spectrin (SPTA) gene using DNA probes. Close linkage was found with a maximum lod score of 5.98 at theta = 0.05. Hybridization to DNA from somatic cell hybrids made from a parent line carrying a balanced X:1 translocation showed both genes to lie proximal to the breakpoint at 1q23. DNA hybridization to cell lines carrying deletions of 1q21-25 showed the presence of two polymorphic alleles for both loci. These results, combined with existing in situ hybridization data, suggest PUM and SPTA both lie within 1q21. Linkage analysis between PUM and the Duffy blood group (FY) gave a maximum lod of 2.15 at theta = 0.15. These data combined with data from another laboratory give a maximum lod of 5.21 for linkage between PUM and FY at theta = 0.10.