We explore the allele and genotype distribution of UGT1A1 and BLVRA variants in individuals affected by neonatal hyperbilirubinemia in southern China. Blood specimens were collected from 240 neonates: 126 cases of hyperbilirubinemia and 114 healthy controls. Serum levels of total protein, albumin, bilirubin (total and direct), urea nitrogen, creatinine, and other biochemical parameters were quantified using a biochemical analyzer. Nine UGT1A1 and five BLVRA genetic variants were genotyped using flight time mass spectrometry. The allele and genotype frequencies of these variants and their associations with neonatal hyperbilirubinemia were analyzed. The genotype frequencies of CC and CG for the UGT1A1 variant rs11888492 in the hyperbilirubinemia group were 90.48% and 9.52%, respectively (
P
= 0.001), in comparison with the control group. The C and G allele frequencies of rs11888492 in the hyperbilirubinemia group were 95.24% and 4.76%, respectively (
P
= 0.023). Similarly, in the hyperbilirubinemia group, the genotype frequencies for the UGT1A1 variant rs4148325 were 90.48% CC, 8.73% CT, and 0.79% TT (
P
= 0.001), with corresponding allele frequencies of 94.84% for C and 5.16% for T (
P
= 0.002). No notable distinctions were detected for other variants. Newborns carrying the CC genotype of rs11888492 exhibited higher total bilirubin (TBIL) levels than those carrying the GG genotype (
P
= 0.034), whereas newborns carrying the CC genotype of rs4148325 displayed higher TBIL levels than those carrying the CT genotype (
P
= 0.003). The presence of the G allele at rs11888492 was found to be significantly correlated with a decreased likelihood of developing neonatal hyperbilirubinemia (odds ratio [OR]: 0.363; 95% confidence interval [CI] 0.169–0.777). Furthermore, a substantial reduction in the risk of neonatal hyperbilirubinemia associated with the CT genotype of rs4148325 were revealed (OR = 0.242; 95% CI 0.102–0.574). Additionally, an inverse relationship was identified between TBIL concentration and the quantity of genetic variants. The UGT1A1 variants rs11888492 and rs4148325 are strongly associated with neonatal hyperbilirubinemia in southern China.
