Genetic heterogeneity of hereditary stomatocytosis syndromes showing pseudohyperkalemia.

genes (genetic heterogeneity). Mapping of the DHSt and FP genes7,9 now allows us to address this problem by means of a linkage analysis. Genomic DNA was obtained from each member of a pedigree described elsewhere.9 Linkage analysis was performed using 8 microsatellite markers (D16S511, D16S3037, D16S520, D16S498, D16S3074, D16S3026, D16S3121) from the chromosome 16 region where we have previously mapped both DHSt and FP.7,8 The analysis reveals the absence of segregation between the above mentioned markers and the disease locus, as shown in Table 1. These results indicate that these pseudohyperkalemic variants are genetically heterogenous with a locus on 16q23 and at least one additional locus, which remains to be mapped. Work is in progress to map this new locus and to understand the molecular basis10 underlying this interesting form of stomatocytosis.