Clinical and Genetic Etiologies of Neonatal Unconjugated Hyperbilirubinemia in the China Neonatal Genomes Project.

OBJECTIVE

To investigate the clinical and genetic causes of neonatal unconjugated hyperbilirubinemia.

STUDY DESIGN

We included 1412 neonates diagnosed with unconjugated hyperbilirubinemia (total serum bilirubin >95 percentile for age), from the China Neonatal Genomes Project between August 2016 and September 2019, in the current study. Clinical data and targeted panel sequencing data on 2742 genes including known unconjugated hyperbilirubinemia genes were analyzed.

RESULTS

Among the 1412 neonates with unconjugated hyperbilirubinemia, 37% had severe unconjugated hyperbilirubinemia, with total serum bilirubin levels that met the recommendations for exchange transfusion. Known clinical causes were identified for 68% of patients. The most common clinical cause in the mild unconjugated hyperbilirubinemia group was infection (17%) and in the severe group was combined factors (21%, with infection combined with extravascular hemorrhage the most common). A genetic variant was observed in 55 participants (4%), including 45 patients with variants in genes associated with unconjugated hyperbilirubinemia and 10 patients with variants that were regarded as additional genetic findings. Among the 45 patients identified with unconjugated hyperbilirubinemia-related variants, the genes were mainly associated with enzyme deficiencies, metabolic/biochemical disorders, and red blood cell membrane defects. G6PD and UGT1A1 variants, were detected in 34 of the 45 patients (76%).

CONCLUSIONS

Known clinical causes, which varied with bilirubin levels, were identified in approximately two-thirds of the patients. Genetic findings were identified in 4% of the patients, including in patients with an identified clinical cause, with G6PD and UGT1A1 being the most common genes in which variants were detected.