Mutations of the BMPR2 gene predispose to pulmonary arterial hypertension (PAH), a serious, progressive disease of the pulmonary vascular system. However, despite the fact that most PAH families are consistent with linkage to the BMPR2 locus, sequencing only identifies mutations in some 55% of familial cases and between 10% and 40% of cases without a family history (idiopathic or IPAH). We therefore conducted a systematic analysis for larger gene rearrangements in panels of both familial and idiopathic PAH cases that were negative on sequencing of coding regions. Analysis of exon dosage across the entire gene using Multiplex Ligation-dependent Probe Amplification identified nine novel rearrangements and enabled full characterization at the exon level of previously reported deletions. Overall, BMPR2 rearrangements were identified in 7 of 58 families and 6 of 126 IPAH cases, suggesting that gross rearrangements underlie around 12% of all FPAH cases and 5% of IPAH. Importantly, two deletions encompassed all functional protein domains and are predicted to result in null mutations, providing the strongest support yet that the predominant molecular mechanism for disease predisposition is haploinsufficiency. Dosage analysis should now be considered an integral of part of the molecular work-up of PAH patients.

Background: The observation that germline mutations in the oxidative DNA damage repair gene MUTYH cause colorectal cancer (CRC) provides strong evidence that dysregulation of the base excision repair (BER) pathway influences disease susceptibility. It is conceivable that germline sequence variation in other BER pathway genes such as NTHL1, NEIL1, NEIL2, MPG, TDG, UNG and SMUG1 also contribute to CRC susceptibility.

Common genetic variation at human 14q22.2 tagged by rs4444235 is significantly associated with colorectal cancer (CRC) risk. Re-sequencing was used to comprehensively annotate the 17kb region of strong linkage disequilibrium encompassing rs4444235. Through bioinformatic analyses using H3K4Me1, H3K4Me3, and DNase-I hypersensitivity chromatin signatures and evolutionary conservation we identified seven candidate disease-causing single-nucleotide polymorphisms mapping to six regions within the 17-kb region predicted to have regulatory potential. Reporter gene studies of these regions demonstrated that the element to which rs4444235 maps acts as an allele-specific transcriptional enhancer. Allele-specific expression studies in CRC cell lines heterozygous for rs4444235 showed significantly increased expression of bone morphogenetic protein-4 (BMP4) associated with the risk allele (Po0.001). These data provide evidence for a functional basis for the noncoding risk variant rs4444235 at 14q22.2 and emphasizes the importance of genetic variation in the BMP pathway genes as determinants of CRC risk.