Scavenger receptor BI (SR-BI) is the major receptor for high-density lipoprotein (HDL) cholesterol (HDL-C). In humans, high amounts of HDL-C in plasma are associated with a lower risk of coronary heart disease (CHD). Mice that have depleted Scarb1 (SR-BI knockout mice) have markedly elevated HDL-C levels but, paradoxically, increased atherosclerosis. The impact of SR-BI on HDL metabolism and CHD risk in humans remains unclear. Through targeted sequencing of coding regions of lipid-modifying genes in 328 individuals with extremely high plasma HDL-C levels, we identified a homozygote for a loss-of-function variant, in which leucine replaces proline 376 (P376L), in SCARB1, the gene encoding SR-BI. The P376L variant impairs posttranslational processing of SR-BI and abrogates selective HDL cholesterol uptake in transfected cells, in hepatocyte-like cells derived from induced pluripotent stem cells from the homozygous subject, and in mice. Large population-based studies revealed that subjects who are heterozygous carriers of the P376L variant have significantly increased levels of plasma HDL-C. P376L carriers have a profound HDL-related phenotype and an increased risk of CHD (odds ratio = 1.79, which is statistically significant).

Abdominal aortic aneurysm (AAA) is a common cause of morbidity and mortality and has a significant heritability. We carried out a genome-wide association discovery study of 1866 patients with AAA and 5435 controls and replication of promising signals (lead SNP with a p value < 1 × 10(-5)) in 2871 additional cases and 32,687 controls and performed further follow-up in 1491 AAA and 11,060 controls. In the discovery study, nine loci demonstrated association with AAA (p < 1 × 10(-5)). In the replication sample, the lead SNP at one of these loci, rs1466535, located within intron 1 of low-density-lipoprotein receptor-related protein 1 (LRP1) demonstrated significant association (p = 0.0042). We confirmed the association of rs1466535 and AAA in our follow-up study (p = 0.035). In a combined analysis (6228 AAA and 49182 controls), rs1466535 had a consistent effect size and direction in all sample sets (combined p = 4.52 × 10(-10), odds ratio 1.15 [1.10-1.21]). No associations were seen for either rs1466535 or the 12q13.3 locus in independent association studies of coronary artery disease, blood pressure, diabetes, or hyperlipidaemia, suggesting that this locus is specific to AAA. Gene-expression studies demonstrated a trend toward increased LRP1 expression for the rs1466535 CC genotype in arterial tissues; there was a significant (p = 0.029) 1.19-fold (1.04-1.36) increase in LRP1 expression in CC homozygotes compared to TT homozygotes in aortic adventitia. Functional studies demonstrated that rs1466535 might alter a SREBP-1 binding site and influence enhancer activity at the locus. In conclusion, this study has identified a biologically plausible genetic variant associated specifically with AAA, and we suggest that this variant has a possible functional role in LRP1 expression.

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Several probiotic strains of Bifidobacterium animalis subsp. lactis are widely supplemented into food products and dietary supplements due to their documented health benefits and ability to survive within the mammalian gastrointestinal tract and acidified dairy products. The strain specificity of these characteristics demands techniques with high discriminatory power to differentiate among strains. However, to date, molecular approaches, such as pulsed-field gel electrophoresis and randomly amplified polymorphic DNA-PCR, have been ineffective at achieving strain separation due to the monomorphic nature of this subspecies. Previously, sequencing and comparison of two B. animalis subsp. lactis genomes (DSMZ 10140 and Bl-04) confirmed this high level of sequence similarity, identifying only 47 single-nucleotide polymorphisms (SNPs) and four insertions and/or deletions (INDELs) between them. In this study, we hypothesized that a sequence-based typing method targeting these loci would permit greater discrimination between strains than previously attempted methods. Sequencing 50 of these loci in 24 strains of B. animalis subsp. lactis revealed that a combination of nine SNPs/INDELs could be used to differentiate strains into 14 distinct genotypic groups. In addition, the presence of a nonsynonymous SNP within the gene encoding a putative glucose uptake protein was found to correlate with the ability of certain strains to transport glucose and to grow rapidly in a medium containing glucose as the sole carbon source. The method reported here can be used in clinical, regulatory, and commercial applications requiring identification of B. animalis subsp. lactis at the strain level.