Coexistence of mutations of Gilbert's syndrome and Crigler-Najjar syndrome in an infant with unconjugated hyperbilirubinemia-a case report

Background Jaundice in the newborn period is a very common entity; rare inherited causes are often forgotten. Persistent unconjugated hyperbilirubinemia in the intermediate levels with non-hemolytic features must prompt the necessity for evaluating for genetic defects in bilirubin metabolism. Case presentation Three-and-a-half-month-old first-born girl of consanguineous marriage presented with jaundice from day 5 of life. Dark yellow color urine or pale stools were not present. Antenatal and birth history was normal. She had mild pallor and icterus and no hepatosplenomegaly. Total serum bilirubin was 8.2 mg/dl, and direct was 0.4 mg/dl. Workup for hemolytic anemia, thyroid function test, and sonography of abdomen was normal. Syrup phenobarbitone was started, and bilirubin levels after dropped to 2 mg/dl. Crigler-Najjar type II syndrome (CN II) or Gilbert's syndrome (GS) was suspected. Next-generation sequencing for UGT1A1 gene mutation showed homozygous missense mutation consistent with CN II and 7 TA repeats in the promoter region consistent with GS. Bilirubin levels gradually fell after starting oral phenobarbitone syrup, and at 5 years of age, a trial of withholding phenobarbitone was given, and bilirubin levels remained lower, and she is asked to follow-up with bilirubin levels every 15 days to assess the need for reintroducing the therapy. Parents are planning for a second pregnancy, and a preconception genetic counseling has been done. Conclusion Genetic confirmation of coexistence of mutations causing GS and CN II have an implication on long-term neurological complications of unconjugated hyperbilirubinemia in stress or crisis situations. Prenatal diagnostic testing must be advised for detecting homozygous UGT1A1 mutations to diagnose CN II and Gilbert mutations for each of the future pregnancies. Considering the side effects of long-term phenobarbitone therapy, the decision can be taken on case-to-case basis of stopping the therapy while monitoring TSB levels.