Cloning of a galactosyl transferase gene promoter to understand the mechanism linking genetic variation to the altered enzyme activity found in IgA nephropathy (360G-Wellcome-202294_Z_16_Z)

IgA nephropathy (IgAN) is the most common glomerulonephritis and is a major cause of kidney failure worldwide. IgAN is characterised by abnormal deposition of galactose-deficient IgA (Gd-IgA) in the kidney, and levels of Gd-IgA are raised in the serum of patients, with levels correlating with clinical outcomes [1, 2]. Why some people have elevated Gd-IgA is unknown, but we have shown that Gd-IgA levels are highly heritable [3, 4] and recently performed a genome wide association study (GWAS) that showed that the presence of a haplotype across a particular galactosyl transferase gene is strongly correlated with Gd-IgA level (p -10), implying that common genetic variation across the locus modulates enzyme activity in the population. Fine mapping of the locus using imputed genotypes, and consultation of available expression quantitative trait loci (eQTL) maps disclosed the set of common variants across the region that might explain the effect, and we now wish to understand the mechanism linking the known genetic variation with altered enzyme activity. The aim of this project is to clone the promoter region of the gene from individuals with and without the associated haplotype for studies using a reporter gene to assess promoter activity of different allotypes.