African American hypertensive nephropathy maps to a new locus on chromosome 9q31-q32
AMERICAN JOURNAL OF HUMAN GENETICS
Authors: Chung, KW; Ferrell, RE; Ellis, D; Barmada, M; Moritz, M; Finegold, DN; Jaffe, R; Vats, A
Abstract
Hypertensive nephropathy (HN) and focal segmental glomerulosclerosis (FSGS) are significant causes of end-stage renal disease ( ESRD), but no genes or loci have been associated with this phenotype among African Americans, a group at high risk. We performed a genomewide linkage scan with similar to400 microsatellite markers on 23 individuals of a large four-generation African American family with 18 affected individuals ( 7 with ESRD), in which the 13-year-old proband (also with ESRD) presented with hypertension and proteinuria (2-4 g/day) and underwent a kidney biopsy that revealed FSGS-like lesions with arteriolar thickening. A genomewide scan revealed LOD scores of 12.5 for markers on chromosomes 3 and 9, and fine mapping was performed on 5 additional members ( total 28 members) that showed a maximum multipoint LOD score of 5.4 in the 9q31-q32 region, under an autosomal dominant model with 99% penetrance. This 8-cM (6-Mb) region is flanked by markers D9S172 and D9S105, and further candidate gene sequencing studies excluded the coding regions of three genes (ACTL7A, ACTL7B, and CTNNAL1). To our knowledge, this is the first report of a locus, denoted as "HNP1," for the HN/FSGS phenotype in a large African American family with dominantly inherited nephropathy characterized by ESRD, hypertension, and some features of FSGS.
Genetic Polymorphisms within The Intronless ACTL7A and ACTL7B Genes Encoding Spermatogenesis-Specific Actin-Like Proteins in Japanese Males
INTERNATIONAL JOURNAL OF FERTILITY & STERILITY
Authors: Tanaka, Hiromitsu; Miyagawa, Yasushi; Tsujimura, Akira; Wada, Morimasa
Abstract
Actins play essential roles in cellular morphogenesis. In mice, the T-actin1 and 2 genes, which encode actin-like proteins, are specifically expressed in haploid germ cells. Both T-ACTIN1/ACTLB and T-ACTIN2/ACTL7A have also been cloned and studied. The orthologous genes in humans are present on chromosome 9q31.3 as intronless genes. Defects of germ cell-specific genes can introduce infertility without somatic function impairment. We determined T-ACTIN1 and 2, specifically expressed in the testis using reverse-transcription polymerase chain reaction (RT-PCR). To examine whether genetic polymorphisms of the T-ACTIN1 and 2 genes are associated with male infertility, we screened for T-ACTIN1 and 2 polymorphisms by direct sequencing of DNA from 282 sterile and 89 fertile Japanese men. We identified five and six single nucleotide polymorphisms (SNPs) in the T-ACTIN1 and 2 regions of the sterile and fertile subjects respectively. Among these genetic polymorphisms was a novel SNP that was not in the National Center for Biotechnology Information SNP database. Although we could not determine whether these SNPs cause infertility, the prevalence of these genetic polymorphisms may be useful for analyzing polymorphisms in future large-scale genetic analyses.