RESUMO
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 dense bodies, and lysosomes. HPS is the most common single-gene disorder in Puerto Rico, with an incidence of 1 in 1,800. We have identified the HPS gene by positional cloning, and found homozygous frameshifts in this 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 clinical phenotypes associated with the different HPS frameshifts we observed suggests that differentially truncated HPS polypeptides may have somewhat different consequences for subcellular function.
Assuntos
Albinismo Oculocutâneo/genética , Citoplasma/genética , Doenças por Armazenamento dos Lisossomos/genética , Proteínas de Membrana/genética , Mutação , Albinismo Oculocutâneo/complicações , Albinismo Oculocutâneo/epidemiologia , Sequência de Aminoácidos , Sequência de Bases , Mapeamento Cromossômico , Clonagem Molecular , Citoplasma/patologia , Regulação da Expressão Gênica , Marcadores Genéticos , Humanos , Irlanda , Japão , Doenças por Armazenamento dos Lisossomos/complicações , Doenças por Armazenamento dos Lisossomos/epidemiologia , Dados de Sequência Molecular , Fenótipo , Porto Rico , Suíça , SíndromeRESUMO
Hermansky-Pudlak syndrome (HPS) is an autosomal recessive disorder characterized by the triad of tyrosinase-positive oculocutaneous albinism, bleeding diathesis due to storage-pool deficiency of platelets, and a lysosomal ceroid storage disease. The disorder is particularly frequent in Puerto Rico and in an isolated village in the Swiss Alps. We have used a linkage disequilibrium mapping approach to localize the HPS gene in both of these groups to a 0.6 centiMorgan interval in chromosome segment 10q23.1-q23.3. These results indicate that the Puerto Rican and Swiss forms of HPS are either allelic or that they result from mutations in very closely linked genes in this region. This region of distal chromosome 10q is syntenic to the region of mouse chromosome 19 that includes 'pale ear' (ep) and 'ruby-eye' (ru), which must be considered as potential murine homologues to human HPS.
Assuntos
Albinismo Oculocutâneo/genética , Cromossomos Humanos Par 10 , Transtornos Hemorrágicos/genética , Desequilíbrio de Ligação , Doenças por Armazenamento dos Lisossomos/metabolismo , Animais , Feminino , Genótipo , Humanos , Masculino , Camundongos , Linhagem , Porto Rico , Suíça , SíndromeRESUMO
Tyrosinase-positive albinism, previously diagnosed as Hermansky-Pudlak Syndrome (HPS), has been examined in four generations from a village of the canton Valais, Switzerland. Homozygotes, obligate heterozygotes and putative heterozygotes in this geneology yielded lower than normal membrane-associated thioredoxin reductase (TR) activities compared with normal family members and controls. All of the homozygotes and 50% of each the obligate and putative heterozygotes showed an increase in bleeding time associated with storage-pool-deficient platelets lacking dense bodies. The TR activity profile and the platelet-dense body deficiency in the Swiss albinos was the same as that in the HPS population from Puerto Rico. However, in albinos from Puerto Rico, there is an accumulation of ceroid/lipofuscin-like pigment in lysosomal structures causing tissue damage, and, upon kidney involvement, this leads to increased urinary dolichol excretion. Approximately half of the Puerto Rican HPS cases had clinical evidence of storage disease with restrictive lung disease, granulomatous colitis, kidney failure and cardiomyopathy. By comparison, the Swiss HPS geneology had a normal life expectancy with no significant evidence for ceroid accumulation or urinary dolichol excretion. An examination of antioxidant enzymes, catalase, TR and glutathione reductase in epidermal suction blisters from Swiss HPS homozygotes showed a similar result for catalase and TR levels to the depigmented epidermis of patients with vitiligo, except that intracellular TR was found to be calcium free in HPS compared with vitiligo. Intracellular glutathione reductase levels were highest in HPS. Both the Swiss and Puerto Rican HPS homozygotes and heterozygotes have giant melanosomes in skin melanocytes.