Molecular, ultrastructural and functional characterization of a Spanish family with Hermansky-Pudlak syndrome: role of insC974 in platelet function and clinical relevance.
Hermansky-Pudlak syndrome (HPS) is a rare autosomal recessive disorder, which is genetically heterogeneous. In humans, mutations associated with this syndrome have been identified that affect four genes, most of them located in the HPS-1 gene. We evaluated the clinical, molecular, platelet ultrastructure and platelet function data obtained from one Spanish HPS patient and his relatives. The proband was compound heterozygous for a de novo nonsense mutation (Arg-131Stop), which has not been described previously, and for a common frameshift mutation (insC974). These two mutations were also identified by reverse transcription polymerase chain reaction (RT-PCR) in half the RNA, supporting the premise that they have minor effects on either transcription or RNA stability. The patient had an almost complete absence of platelet-dense granules. Accordingly, his platelets showed a small aggregatory response, reduced CD63 surface expression after platelet activation and minor serotonin uptake. Interestingly, despite the absence of clinical symptoms, two relatives carrying only one HPS-1 mutation (insC974) presented a decreased content of platelet-dense granules and showed significant reductions in platelet aggregation, expression of CD63 after platelet activation and serotonin uptake. Data show that the presence of a single mutation affecting one allele of the HPS-1 gene might have relevance in the organogenesis of platelet-dense granules, affecting platelet function. However, these functional defects were not of a great enough magnitude to have clinical significance and, thus, these subjects were clinically asymptomatic.
D001792:Blood Platelets / Q000378:metabolism / Q000648:ultrastructure*; D002648:Child; D018389:Codon, Nonsense; D003594:Cytoplasmic Granules / Q000378:metabolism / Q000648:ultrastructure; D005434:Flow Cytometry; D016368:Frameshift Mutation; D022861:Hermanski-Pudlak Syndrome / Q000097:blood / Q000235:genetics*; D006579:Heterozygote; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D010375:Pedigree; D010974:Platelet Aggregation; D012701:Serotonin / Q000378:metabolism; D013030:Spain
D018389:Codon, Nonsense; C102160:HPS1 protein, human; D008565:Membrane Proteins; D012701:Serotonin