Logo image
Detection of hemizygosity in Hermansky - Pudlak syndrome by quantitative real-time PCR
Journal article   Peer reviewed

Detection of hemizygosity in Hermansky - Pudlak syndrome by quantitative real-time PCR

A E Griffin, B R Cobb, P D Anderson, D A Claassen, A Helip-Wooley, M Huizing and W A Gahl
Clinical genetics, Vol.68(1), pp.23-30
Received 4 February 2005, revised and accepted for publication 29 March 2005
07/2005
DOI: 10.1111/j.1399-0004.2005.00461.x
PMID: 15952982

View Online

Abstract

Hermansky-Pudlak syndrome (HPS) is an autosomal recessive disorder characterized by oculocutaneous albinism, a bleeding diathesis and, in some patients, pulmonary fibrosis or granulomatous colitis. HPS is associated with biosynthesis defects of melanosomes, platelet-dense bodies, and lysosomes. There are seven genetic HPS subtypes; HPS-1 is the most common. We used a real-time quantitative PCR (qPCR) approach to investigate six HPS-1 patients, previously assigned as having homozygous mutations in the HPS1 gene. HPS1 gene copy numbers, calculated by use of a comparative Ct method, revealed that one patient was in fact hemizygous for her c.1189delC (S396delC) HPS1 mutation. The causative deletion/insertion was 13,966 bp in size, with defined breakpoints, and involved an adjacent gene (C10orf33). A mechanism of formation is proposed for the deletion/insertion, and both multiplex and qPCR indicated that the deletion/insertion was present in the patient, her brother, and her father. qPCR amplification is valuable for detecting deletions too small to be identified by fluorescence in situ hybridization. This demonstration of hemizygosity, performed using genomic DNA, can eliminate concerns about non-paternity and can verify the diagnosis of an autosomal recessive disorder when a DNA alteration appears to be homozygous by standard PCR and sequencing methods, and its pathogenicity is in doubt.
hemizygosity C10orf33 Hermansky-Pudlak syndrome genomic insertion/ deletion real-time quantitative PCR breakpoint

Details

Logo image