POSITIONAL CLONING OF A GENE FOR HERMANSKY-PUDLAK SYNDROME, A DISORDER OF CYTOPLASMIC ORGANELLES

Hermansky-Pudlak syndrome (HPS) is an often-fatal autosomal recessive disease in which albinism, bleeding, and lysosomal storage result from defects of diverse cytoplasmic organelles: melanosomes, platelet dens e bodies, and lysosomes. HPS is the most common single-gene disorder i n Puerto Rico, with an incidence of 1 in 1,800. We have identified the HPS gene by positional cloning, and found homozygous frameshifts in t his gene in Puerto Rican, Swiss, Irish and Japanese HPS patients. The HPS polypeptide is a novel transmembrane protein that is likely to be a component of multiple cytoplasmic organelles and that is apparently crucial for their normal development and function. The different clini cal phenotypes associated with the different HPS frameshifts we observ ed suggests that differentially truncated HPS polypeptides may have so mewhat different consequences for subcellular function.