Table 5.

BCAA-related gene variants in specific tissues based on included studies.

Study	BCAA and related metabolites identified	Identified gene variants	Specific tissue
Boulet et al. [32]	Leucine, histidine, isoleucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine, alanine, arginine, citrulline, cystine, glycine, ornithine, proline, serine, taurine, tyrosine, C3	BCKDHA, BCKDHB, BCAT1, BCAT2, BCKDK	Visceral adipose tissue, subcutaneous adipose tissue
Badoud et al. [33]	Valine, isoleucine, ornithine, alanine, aspartic acid, glutamine, phenylalanine, methionine, tyrosine, glycine, cysteine, aspartic acid, glutamine/glutamic acid	BCAT2, BCKDHA, BCKDHB, DBT,	Subcutaneous adipose tissue
Serralde-Zúñiga et al. [39]	Total BCAA, isoleucine, leucine, valine	BCAT2, BCKDH E1a, SREBP-1, FTO	Omental adipose tissue
Xu et al. [22]	Valine, isoleucine, leucine, tyrosine, phenylalanine, tryptophan, BCAA/AAA	PPM1K (rs 1440581), C allele	Blood
Naukkarinen et al. [27]	Leucine, isoleucine, valine, alanine, phenylalanine, tyrosine, glutamine, glutamate/glutamine	Genes of BCAA catabolism (monozygotic twin study)	Subcutaneous adipose tissue
Würtz et al. [28]	Leucine, isoleucine, valine, glutamine, pyruvate, creatinine, alanine, phenylalanine, phospholipids, fatty acids	GCKR (rs 1260326)	Blood

Note: IR: insulin resistance; BCAA: branched-chain amino acids; AAA: aromatic amino acids; BCKDK: branched-chain keto acid dehydrogenase kinase; BCKDHE1a (BCKDHA): branched-chain keto acid dehydrogenase E1, alpha polypeptide; BCKDHB: branched-chain keto acid dehydrogenase E1 subunit beta; BCAT1: branched-chain amino acid transaminase 1; BCAT2: branched-chain amino acid transaminase 2; DBT: dihydrolipoamide branched-chain transacylase E2; SREBP-1: sterol regulatory element binding protein 1; FTO: fat mass and obesity associated; PPM1K: protein phosphatase, Mg2+/Mn2+ dependent 1K; GCKR: glucokinase (hexokinase 4) regulator.