Objective To explore the etiological characteristics of severe hyperbilirubinemia in full-term newborns of eastern Guangdong. Methods Full-term newborns with severe hyperbilirubinemia in one hospital from January 2012 to December 2021 were retrospectively analyzed. The etiology was determined according to the laboratory results and clinical manifestations. Results Among 1602 full-term newborns with hyperbilirubinemia in Chaozhou area, 32.20% (580/1602) was severe hyperbilirubinemia, including 213 newborns with TSB levels reaching the recommended exchange transfusion levels and 52 cases diagnosed with prolonged jaundice. Among the causes of severe hyperbilirubinemia, neonatal hemolysis accounted for 15.17%, infection accounted for 10.17%, G6PD deficiency accounted for 9.13%, and the coexistence of multiple etiologies accounted for 6.55%, unknown etiology accounted for 50.00%. ABO hemolysis and G6PD deficiency were the most common causes in the 20 cases with bilirubin encephalopathy. 94 severe hyperbilirubinemia newborns were tested for UGT1A1*6 variant (rs4148323, c.211G > A, p.Arg71Gly,), 9 cases were 211 G to A homozygous variant, 37 cases were 211 G to A heterozygous variant, and 48 cases were wild genotypes. Conclusion The main cause for severe hyperbilirubinemia and bilirubin encephalopathy were the hemolytic disease of the newborn, G6PD deficiency and infection. UGT1A1 gene variant was also a high risk factor for neonatal hyperbilirubinemia. Targeted prevention and treatment according to the etiology may reduce the occurrence of bilirubin encephalopathy and kernicterus.

Background: Neonatal hyperbilirubinemia causing jaundice is common in East Asian population. Uridine diphosphate glucuronosyltransferase isoenzyme (UGT1A1) glucuronidates bilirubin and converts the toxic form of bilirubin to its nontoxic form.Method: A retrospective study was conducted to review clinical information of ABO hemolysis neonates (ABO HDN) admitted to the Department of Neonatology, referred for neonatal hyperbilirubinemia, in a large general hospital of southern China from 2011 to 2017. Variation status of UGT1A1 was determined by direct sequencing or genotype assays.Result: Sixty-nine ABO HDNs were included into the final analysis. UGT1A1 c.211 G>A mutation (UGT1A1*6, p.Arg71Gly, rs4148323) was significantly associated with the increased bilirubin level in ABO HDNs, after adjusted by age, sex and feeding method (P=0.019 for TBIL, P=0.021 for IBIL). Moreover, heterozygous and/or homozygous UGT1A1 mutations in the coding sequence region were significantly associated with the increased risk of developing hazardous hyperbilirubinemia (as defined by TSB>427 umol/L) as compared those with a normal UGT1A1 genotype (ORadj=9.16, 95%CI 1.99- 42.08, P=0.002) in the study cohort.Conclusion: UGT1A1 variant in coding region is actively involved in the pathogenesis of ABO hemolysis related neonatal hyperbilirubinemia. Genetic assessment of UGT1A1 may be useful for clinical diagnosis of neonatal unconjugated hyperbilirubinemia.

<b><i>Introduction:</i></b> Neonatal hyperbilirubinemia is common and remains a clinical concern in China. Since neonatal hyperbilirubinemia is linked to genetic factors, we aimed to identify the gene variants of the red blood cell membrane (RBCM) and evaluate the clinical risk factors in Chinese neonates with hyperbilirubinemia. <b><i>Methods:</i></b> 117 hyperbilirubinemia neonates (33 cases of moderate hyperbilirubinemia and 84 cases of severe hyperbilirubinemia) and 49 controls with normal bilirubin levels were selected as our study subjects. A customized 22-gene panel with next-generation sequencing (NGS) was designed to characterize genetic variations among the neonates. Sanger sequencing was used to verify the accuracy of the NGS. The clinical risk factors and potential effects of genetic variations in neonates with hyperbilirubinemia were subsequently assessed. <b><i>Results:</i></b> After data filtering, suspected pathogenic variants of UGT1A1, SLCCO1B1, and RBCM-associated gene were identified in neonates, the combined numbers of RBCM-associated gene variants were found to have differences between the hyperbilirubinemia group and the controls (<i>p</i> = 0.008), they were also different between severe hyperbilirubinemia and moderate hyperbilirubinemia (<i>p</i> = 0.008), and were correlated with an increased risk of hyperbilirubinemia (odds ratio = 9.644, <i>p</i> = 0.006). The <i>UGT1A1</i>-rs4148323 variant in neonates with hyperbilirubinemia was significantly increased as compared with the controls (<i>p</i> &#x3c; 0.001). However, there was no statistical difference for the <i>SLCO1B1</i>-rs2306283 variant between the hyperbilirubinemia group and the controls. In addition, breastfeeding contributed to an increased risk of hyperbilirubinemia. <b><i>Conclusion:</i></b> Our study highlights that the RBCM-related gene variants are an underestimated risk factor, which may play an important role in developing hyperbilirubinemia in Chinese newborns.