Estimating genetic load from 5000 Chinese exomes

Recent advancements in genome sequencing have enabled the estimation of genetic load through deleterious mutation profiling. However, Chinese populations remain underexplored in this context. We analyze whole-exome sequencing data from 5002 individuals, encompassing major Han subgroups-North Han (N-Han), South Han (S-Han), and Guangxi Han (G-Han)-as well as 13 ethnic minorities. Notably, G-Han exhibits significant genetic affinity with the Zhuang population. Systematic curation of 2110 ClinVar pathogenic or likely pathogenic variants reveals 93.4% are ultra-rare. Exceptions include GJB2 rs72474224-A (hearing loss), which shows higher frequencies in Zhuang and G-Han, and β-thalassemia-associated HBB variants (rs33986703-A and rs33950507-T), which are elevated in G-Han compared to other Han subgroups. Among 96 autosomal dominant mutation carriers, LDLR variants are predominant (∼25%), with comparable frequencies across Han subgroups. Adaptive signatures highlight gene-environment interactions: MTHFR rs1801133-A (UV adaptation) declines southward, while ALDH2 rs671-A (alcohol metabolism) displays the opposite trend. ABCC11 rs17822931-A, associated with cold adaptation, is particularly low frequency in G-Han. Gene-based rare-variant collapsing analyses identify an elevated risk of retinitis pigmentosa in S-Han (PRPF4, TUB). Our findings demonstrate that genetic load in Chinese populations is influenced by demographic history, population structure, and regional adaptation, emphasizing the importance of population-specific frameworks in precision medicine.