GWAS on longitudinal growth traits reveals different genetic factors influencing infant, child, and adult BMI

Early childhood growth patterns are associated with adult health, yet the genetic factors and the developmental stages involved are not fully understood. Here, we combine genome-wide association studies with modeling of longitudinal growth traits to study the genetics of infant and child growth, followed by functional, pathway, genetic correlation, risk score, and colocalization analyses to determine how developmental timings, molecular pathways, and genetic determinants of these traits overlap with those of adult health. We found a robust overlap between the genetics of child and adult body mass index (BMI), with variants associated with adult BMI acting as early as 4 to 6 years old. However, we demonstrated a completely distinct genetic makeup for peak BMI during infancy, influenced by variation at the LEPR/LEPROT locus. These findings suggest that different genetic factors control infant and child BMI. In light of the obesity epidemic, these findings are important to inform the timing and targets of prevention strategies.

Pharmacokinetics and pharmacogenetics of the MEK1/2 inhibitor, selumetinib, in Asian and Western healthy subjects: a pooled analysis

Purpose

Emerging data on selumetinib, a MEK1/2 inhibitor in clinical development, suggest a possible difference in pharmacokinetics (PK) between Japanese and Western patients. This pooled analysis sought to assess the effect of ethnicity on selumetinib exposure in healthy Western and Asian subjects, and to identify any association between genetic variants in the UGT1A1, CYP2C19 and ABCG2 genes and observed differences in selumetinib PK.

Methods

A pooled analysis of data from ten Phase I studies, one in Asian subjects (encompassing Japanese, non-Japanese Asian and Indian Asian subjects) and nine in Western subjects, was conducted. Key findings were derived from the collective exposure data across doses of 25, 35, 50 and 75 mg selumetinib; primary variables were dose-normalized AUC and C_max.

Results

PK data from 308 subjects (10 studies) were available for the pooled analysis; genetic data from 87 subjects (3 studies) were available for the pharmacogenetic analysis. Dose-normalized AUC and C_max were 35% (95% CI: 25–47%) and 39% (95% CI: 24–56%) higher in the pooled Asian group, respectively, compared with Western subjects. PK exposure parameters were similar between the Japanese, non-Japanese Asian and Indian groups. There was no evidence that the polymorphisms assessed in the genes UGT1A1, CYP2C19 and ABCG2 account for observed PK differences.

Conclusions

Selumetinib exposure was higher in healthy Asian subjects compared with Western subjects, and these data provide valuable insight for clinicians to consider when treating patients of Asian ethnicity with selumetinib.

Electronic supplementary material

The online version of this article (doi:10.1007/s00228-017-2217-3) contains supplementary material, which is available to authorized users.

DNA methylation signatures of chronic low-grade inflammation are associated with complex diseases

BACKGROUND

Chronic low-grade inflammation reflects a subclinical immune response implicated in the pathogenesis of complex diseases. Identifying genetic loci where DNA methylation is associated with chronic low-grade inflammation may reveal novel pathways or therapeutic targets for inflammation.

RESULTS

We performed a meta-analysis of epigenome-wide association studies (EWAS) of serum C-reactive protein (CRP), which is a sensitive marker of low-grade inflammation, in a large European population (n = 8863) and trans-ethnic replication in African Americans (n = 4111). We found differential methylation at 218 CpG sites to be associated with CRP (P < 1.15 × 10^-7) in the discovery panel of European ancestry and replicated (P < 2.29 × 10^-4) 58 CpG sites (45 unique loci) among African Americans. To further characterize the molecular and clinical relevance of the findings, we examined the association with gene expression, genetic sequence variants, and clinical outcomes. DNA methylation at nine (16%) CpG sites was associated with whole blood gene expression in cis (P < 8.47 × 10^-5), ten (17%) CpG sites were associated with a nearby genetic variant (P < 2.50 × 10^-3), and 51 (88%) were also associated with at least one related cardiometabolic entity (P < 9.58 × 10^-5). An additive weighted score of replicated CpG sites accounted for up to 6% inter-individual variation (R2) of age-adjusted and sex-adjusted CRP, independent of known CRP-related genetic variants.

CONCLUSION

We have completed an EWAS of chronic low-grade inflammation and identified many novel genetic loci underlying inflammation that may serve as targets for the development of novel therapeutic interventions for inflammation.

DNA mismatch repair gene MSH6 implicated in determining age at natural menopause

The length of female reproductive lifespan is associated with multiple adverse outcomes, including breast cancer, cardiovascular disease and infertility. The biological processes that govern the timing of the beginning and end of reproductive life are not well understood. Genetic variants are known to contribute to ∼50% of the variation in both age at menarche and menopause, but to date the known genes explain <15% of the genetic component. We have used genome-wide association in a bivariate meta-analysis of both traits to identify genes involved in determining reproductive lifespan. We observed significant genetic correlation between the two traits using genome-wide complex trait analysis. However, we found no robust statistical evidence for individual variants with an effect on both traits. A novel association with age at menopause was detected for a variant rs1800932 in the mismatch repair gene MSH6 (P = 1.9 × 10(-9)), which was also associated with altered expression levels of MSH6 mRNA in multiple tissues. This study contributes to the growing evidence that DNA repair processes play a key role in ovarian ageing and could be an important therapeutic target for infertility.