Genome-wide study of familial juvenile hyperuricaemic (gouty) nephropathy (FJHN) indicates a new locus, FJHN3, linked to chromosome 2p22.1-p21
HUMAN GENETICS
Authors: Piret, Sian E.; Danoy, Patrick; Dahan, Karin; Reed, Anita A. C.; Pryce, Karena; Wong, William; Torres, Rosa J.; Puig, Juan G.; Mueller, Thomas; Kotanko, Peter; Lhotta, Karl; Devuyst, Olivier; Brown, Matthew A.; Thakker, Rajesh V.
Abstract
Familial juvenile hyperuricaemic (gouty) nephropathy (FJHN), is an autosomal dominant disease associated with a reduced fractional excretion of urate, and progressive renal failure. FJHN is genetically heterogeneous and due to mutations of three genes: uromodulin (UMOD), renin (REN) and hepatocyte nuclear factor-1beta (HNF-1 beta) on chromosomes 16p12, 1q32.1, and 17q12, respectively. However, UMOD, REN or HNF-1 beta mutations are found in only similar to 45% of FJHN probands, indicating the involvement of other genetic loci in similar to 55% of probands. To identify other FJHN loci, we performed a single nucleotide polymorphism (SNP)-based genome-wide linkage analysis, in six FJHN families in whom UMOD, HNF-1 beta and REN mutations had been excluded. Parametric linkage analysis using a 'rare dominant' model established linkage in five of the six FJHN families, with a LOD score >+3, at 0% recombination, between FJHN and SNPs at chromosome 2p22.1-p21. Analysis of individual recombinants in two unrelated affected individuals defined a similar to 5.5 Mbp interval, flanked telomerically by SNP RS372139 and centromerically by RS896986 that contained the locus, designated FJHN3. The interval contains 28 genes, and DNA sequence analysis of the most likely candidate, solute carrier family 8 member 1 (SLC8A1), did not identify any abnormalities in the FJHN3 probands. FJHN3 is likely located within a similar to 5.5 Mbp interval on chromosome 2p22.1-p21, and identifying the genetic abnormality will help to further elucidate mechanisms predisposing to gout and renal failure.
Genetic predisposition for glomerulonephritis-induced glomerulosclerosis in rats is linked to chromosome 1
PHYSIOLOGICAL GENOMICS
Authors: IJpelaar, Daphne H. T.; Schulz, Angela; Aben, Joris; van der Wal, Annemieke; Bruijn, Jan A.; Kreutz, Reinhold; de Heer, Emile
Abstract
IJpelaar DH, Schulz A, Aben J, van der Wal A, Bruijn JA, Kreutz R, de Heer E. Genetic predisposition for glomerulonephritisinduced glomerulosclerosis in rats is linked to chromosome 1. Physiol Genomics 35: 173-181, 2008. First published August 5, 2008; doi:10.1152/physiolgenomics.00268.2007.-Genetic factors influence renal disease progression, and several loci have been linked to the spontaneous development of proteinuria and glomerulosclerosis in animal models. However, the role of genetic susceptibility in glomerulonephritisinduced progressive glomerulosclerosis is unknown. In a rat model of mesangial proliferative glomerulonephritis, anti-Thy-1 glomerulonephritis (antiThy1GN), Lewis/Maastricht (Lew/Maa) rats exhibit progression to glomerulosclerosis, whereas in genetically related Lewis/Mollegard (Lew/Moll) rats, glomerular lesions are repaired within 3 wk. The genetic factors underlying this strain-related difference are not known. To identify novel quantitative trait loci (QTL) involved in progression or repair in Lewis rats, 145 female backcross rats [F1(Lew/Maa x Lew/Moll) x Lew/Maa] were studied. After induction of antiThy1GN proteinuria, we determined mesangial activation, the percentage of microaneurysms, and the glomerular damage score for each animal; a genome scan using 187 microsatellite markers was performed. QTL mapping revealed a significant QTL for glomerular damage score on chromosome 1 with a logarithm of odds (LOD) score of 3.9. Homozygosity for Lew/Maa DNA in this region was associated with a higher percentage of damaged glomeruli on day 21. Furthermore, suggestive linkage was found for the percentage of glomeruli with microaneurysms on day 3 on chromosome 1, 6, and 11; for mesangial activation on day 7 on chromosome 18, while proteinuria was suggestively linked to chromosome 5 (day 0), 4 (day 3), and 6 (day 7). This study identifies a QTL on rat chromosome 1 that is significantly linked to progressive glomerulosclerosis after acute glomerulonephritis.