Appendicular lean mass (ALM) is a heritable trait associated with loss of lean muscle mass and strength, or sarcopenia, but its genetic determinants are largely unknown. Here we conducted a genome-wide association study (GWAS) with 450,243 UK Biobank participants to uncover its genetic architecture. A total of 1059 conditionally independent variants from 799 loci were identified at the genome-wide significance level (p < 5 × 10⁻⁹), all of which were also significant at p < 5 × 10^–5 in both sexes. These variants explained ~15.5% of the phenotypic variance, accounting for more than one quarter of the total ~50% GWAS-attributable heritability. There was no difference in genetic effect between sexes or among different age strata. Heritability was enriched in certain functional categories, such as conserved and coding regions, and in tissues related to the musculoskeletal system. Polygenic risk score prediction well distinguished participants with high and low ALM. The findings are important not only for lean mass but also for other complex diseases, such as type 2 diabetes, as ALM is shown to be a protective factor for type 2 diabetes.

A new quassinoid, shinjulactone O (1), and seven known quassinoids, were isolated from the 50% ethanol extract of the root bark of Ailanthus altissima. The structures of these compounds were determined based on spectroscopic methods including UV, IR, HR-ESI-MS, 1D and 2D NMR. Their cytotoxic activities were evaluated on the tumour cell lines MCF-7, MDA-MB-231, HepG2 and A549 cells, as well as the normal HUVEC line in vitro. Compounds 1–8 exhibited different levels of inhibitory activity against tumour cell lines.