Abstract
Family studies have established that the heritability of blood pressure is significant and genome-wide association studies (GWAS) have identified numerous susceptibility loci, including one within the non-coding part of Rho GTPase-activating protein 42 gene (ARHGAP42) on chromosome 11q22.1. Arhgap42-deficient mice have significantly elevated blood pressure, but the phenotypic effects of human variants in the coding part of the gene are unknown. In a Danish cohort of carriers with apparently balanced chromosomal rearrangements, we identified a family where a reciprocal translocation t(11;18)(q22.1;q12.2) segregated with hypertension and obesity. Clinical re-examination revealed that four carriers (age 50-77 years) have had hypertension for several years along with an increased body mass index (34-43 kg/m(2)). A younger carrier (age 23 years) had normal blood pressure and body mass index. Mapping of the chromosomal breakpoints with mate-pair and Sanger sequencing revealed truncation of ARHGAP42. A decreased expression level of ARHGAP42 mRNA in the blood was found in the translocation carriers relative to controls and allele-specific expression analysis showed monoallelic expression in the translocation carriers, confirming that the truncated allele of ARHGAP42 was not expressed. These findings support that haploinsufficiency of ARHGAP42 leads to an age-dependent hypertension. The other breakpoint truncated a regulatory domain of the CUGBP Elav-like family member 4 (CELF4) gene on chromosome 18q12.2 that harbours several GWAS signals for obesity. We thereby provide additional support for an obesity locus in the CELF4 domain.