HOMOZYGOSITY MAPPING, TO CHROMOSOME 11P, OF THE GENE FOR FAMILIAL PERSISTENT HYPERINSULINEMIC HYPOGLYCEMIA OF INFANCY

Familial persistent hyperinsulinemic hypoglycemia of infancy (PHHI) is a rare, autosomal recessive disease of unregulated insulin secretion, defined by elevations in serum insulin despite severe hypoglycemia. W e used the homozygosity gene-mapping strategy to localize this disorde r to the region of chromosome 11p between markers D11S1334 and D11S899 (maximum LOD score 5.02 [theta = 0] at marker D11S926) in five consan guineous families of Saudi Arabian origin. These results extend those of a recent report that also placed PHHI on chromosome 11p, between ma rkers D11S926 and D11S928. Comparison of the boundaries of these two o verlapping regions allows the PHHI locus to be assigned to the 4-cM re gion between the markers D11S926 and D11S899. Identification of this g ene may allow a better understanding of other disorders of glucose hom eostasis, by providing insight into the regulation of insulin release.