Unraveling genetic underpinnings of purine content in pork

The significance of purine base content as an important nutrition indicator in foods arises from its potential to trigger hyperuricemia or gout via high-purine diet. Livestock meats, including pork, generally contain moderate to high total purine content (TP). Recent research revealed substantial variations within and across pig breeds, implying genetic factors influencing this trait. Thus, this study aimed to unravel the genetic underpinnings governing purine base content in pork. The heritability estimates (h2) for the four purine traits ranged from 0.14 to 0.35. A total of 14, 36, 19 and 25 quantitative trait loci (QTLs) were identified for guanine, adenine, hypoxanthine, and TP, respectively. Our comprehensive gene set enrichment analysis and gene network analysis revealed 15 promising candidate genes intricately interwoven within diverse purine metabolism pathways, such as purine ribonucleotide metabolic process, purine nucleotide metabolism and transport, and purine salvage pathways, all contributing to TP. Strikingly, most genetic variants significantly associated with TP displayed analogous effects on multiple purine bases. Two distinct and highly significant QTLs (P < 10-12) emerged on Sus Scrofa chromosome (SSC) 12: one impacting guanine content and the other concurrently influencing adenine and hypoxanthine levels. The peak of the guanine QTL on SSC12 resided 1.1 kb downstream of the transmembrane protein 238 like (TMEM238L) gene and is encapsulated within a genomic segment characterized by the histone modification H3K27me3. Focused fine-mapping for the SSC12 QTL associated with adenine and hypoxanthine levels narrowed its scope to around 172 kb, encompassing the growth arrest specific 7 (GAS7) and myosin heavy chain 13 (MYH13) genes. However, the observed QTL effect was not attributed to any missense mutations within the two genes. This pioneering study unveils the genetic variations and candidate genes associated with purine content in livestock, laying a robust foundation for the selective breeding of pig lines with reduced purine base content.