Cloning and characterization of the human choroideremia gene

Abstract

Positional cloning has previously resulted in the identification of a gene which is disrupted by deletions in patients with the classic choroideremia (CHM) phenotype. More subtle mutations had been identified in 4 exons of the 3' portion but not elsewhere in the CHM gene. We have now isolated and characterized the complete open reading frame of the CHM gene and determined its exon-intron structure. The CHM gene encodes a protein of 653 amino acids, which is highly homologous to the mouse and rat CHM proteins, and, to a slightly lesser extent, to the human CHM-like (CHML) protein. The open reading frame (ORF) of the human CHM gene consists of 15 exons, spanning at least 150 kb of Xq21.2, and it is possible that there is an additional exon corresponding to the 5' non-coding region of the gene. Cloning of the 5' end of the CHM gene and the elucidation of its intron-exon structure enabled us to localize the X-chromosomal breakpoint in a CHM female with an X;7 translocation between exons 3 and 4.

Yeast Artificial Chromosome Cloning of the Xq13.3-q21.31 Region and Fine Mapping of a Deletion Associated with Choroideremia and Nonspecific Mental Retardation

“…results]. Moreover, we have previously de scribed a 850-kb YAC and cosmid contig encompassing the D FN 3 locus and a 350-kb YAC encompassing the CHM gene [9,12,13], Here, we report on three Y AC contigs span ning approximately 7 Mb o f the Xql3.3-q21.31 region and on the localization of a novel deletion associated with CHM and MR.…”

“…Sizeable deletions have also been found in patients with nonsyndromic CHM or DFN3 [4-6, 8,9], Employing positional cloning strategies, the genes underlying CHM and DFN3 have been isolated. Analysis of patients with Xq21 deletions and syndromic and nonsyndromic forms of MR has enabled us to map the gene for X-linked MR to a region between CHM and DFN3 [4,7,[10][11][12][13].…”

Gene Therapy for Choroideremia Using an Adeno-Associated Viral (AAV) Vector

“…Fortunately, this has previously been fully cloned and characterized (Cremers et al 1990;van Bokhoven et al 1994). Overall, each AAV virion would contain a single stranded DNA sequence of 4.2 kb in length comprising a CMV enhancer/CBA hybrid promoter, human REP1 cDNA, WPRE, and bovine growth hormone polyadenylation sequence (BGH-polyA).…”

Clinical utility gene card for: Choroideremia

“…Translocations between the X-chromosome and an autosome, disrupting CHM have been detected in females (but not males), displaying mild clinical signs of choroideremia and ovarian dysgenesis; t(X;7)(q21.2;p12), t(X;13)(q21.2;p12) and t(X;4)(q21.2; p16.3). [4][5][6] A fourth complex translocation involving chromosomes X, 1 and 3: t(X;1;3)(q13;q24;q21),inv(9)(p11q13) has been identified in a female carrier with a severe choroideremia phenotype (thought to be due to nonrandom inactivation of the normal X-chromosome) and ectodermal dysplasia, with no comment of gonadal dysgenesis. 7 …”