New Type of Mutations in Three Spanish Families with Choroideremia

• Published in: Investigative ophthalmology & visual science Vol. 49; no. 4; pp. 1315 - 1321
• Main Authors: Garcia-Hoyos, Maria, Lorda-Sanchez, Isabel, Gomez-Garre, Pilar, Villaverde, Cristina, Cantalapiedra, Diego, Bustamante, Ana, Diego-Alvarez, Dan, Vallespin, Elena, Gallego-Merlo, Jesus, Trujillo, Maria Jose, Ramos, Carmen, Ayuso, Carmen
• Format: Journal Article
• Language: English
• Published: Rockville, MD ARVO 01.04.2008; Association for Research in Vision and Ophtalmology
• Subjects: Adaptor Proteins, Signal Transducing - genetics; Biological and medical sciences; Blotting, Southern; Choroideremia - genetics; DNA Mutational Analysis; European Continental Ancestry Group - genetics; Eye and associated structures. Visual pathways and centers. Vision; Female; Fundamental and applied biological sciences. Psychology; Haplotypes; Humans; Immunoblotting; Male; Medical sciences; Mutation; Ophthalmology; Pedigree; Polymerase Chain Reaction; rab GTP-Binding Proteins - genetics; Retinopathies; RNA, Messenger - genetics; Spain; Vertebrates: nervous system and sense organs; Eye disease; Family study; Choroideremia; Family environment; Uvea disease; Mutation; Ophthalmology; Genetic disease
• ISSN: 0146-0404; 1552-5783; 1552-5783
• DOI: 10.1167/iovs.07-1169

Choroideremia (CHM) is an X-linked ophthalmic disease. The gene associated with CHM (REP-1) encodes a ubiquitously expressed protein that is indispensable for the posttranslational activation of retina-specific Rab protein. Different mutations, including large genomic rearrangements involving the REP-1 gene, are responsible for CHM, but they all cause the protein to be truncated or absent. The authors screened 20 Spanish families with clinical diagnoses of CHM to determine the molecular cause of the disease. First, the authors performed haplotype analyses to determine whether the disease is linked to the REP-1 gene. In families in whom the disease segregated with the CHM locus (n = 14), mutational screening of the REP-1 gene was performed. In 13 of the 14 families in which the phenotype segregated with the CHM locus, the authors identified the mutation associated with the disease. Eight different molecular defects that led to truncation and one that led to complete absence of the REP-1 protein were found in nine families and one family, respectively. Furthermore, the authors identified a novel type of mutation in the REP-1 gene in three families. This novel type of mutation did not result in a truncated or absent protein. Rather, these patients lost different parts of the REP-1 mRNA in-frame that in all the cases encode a conserved protein domain implicated in the interaction with Rab proteins. Based on the different mutations found, the authors propose a four-step protocol for the molecular diagnosis of CHM.