UGT1A1Gene Mutations in Pakistani Children Suffering from Inherited Nonhemolytic Unconjugated Hyperbilirubinemias

Liver Transplantation in a Child With Crigler-Najjar Syndrome Type I: A Case Report With Review of the Literature

Crigler-Najjar syndrome (CNS) type I is a rare genetic disease caused by mutations in the UGT1A1 gene, resulting in a lack of Uridine 5'-diphospho-glucuronosyltransferase (UDPGT) enzyme. This enzyme is responsible for the glucuronidation and elimination of unconjugated bilirubin from the body. Here we report a two-month-old Saudi girl who presented with persistent unconjugated hyperbilirubinemia, reaching levels as high as 30 mg/dL despite ineffective phototherapy. The diagnosis was confirmed through sequencing, and the patient underwent a successful liver transplant at the age of two months. At the one-year follow-up, the patient is doing well. This case highlights the significance of early detection and appropriate management of CNS, emphasizing the need for prompt intervention to improve patient outcomes and prevent complications. While phototherapy offers some benefits, liver transplantation remains the only definitive treatment for this condition.

Spectrum of UGT1A1 variants in Pakistani children affected with inherited unconjugated hyperbilirubinemias

Inherited unconjugated hyperbilirubinemias are a group of disorders characterized by increased levels of serum unconjugated bilirubin and arise because of the imbalance between its production and elimination from the body. It includes Crigler-Najjar syndrome and Gilbert syndrome. Crigler-Najjar syndrome type 1 represents the extreme severe end of the spectrum with complete absence of hepatic bilirubin uridine diphosphoglucuronate glucuronosyltransferase (UGT1A1). Crigler-Najjar syndrome type 2 patients have intermediate levels of bilirubin owing to incomplete deficiency of UGT1A1, and Gilbert syndrome lies at the extreme mild end of the spectrum with only slightly raised bilirubin level. Here, we present spectrum of UGT1A1 genetic variants in 25 Pakistani children from 23 unrelated families affected with persistent unconjugated hyperbilirubinemias. The promoter region, coding exons and splice junctions of the UGT1A1 were PCR amplified and subjected to Sanger sequencing. Eleven sequence variants were identified underlying disease phenotype including a novel c.582delC variant. Overall, c.622_625dupCAGC was the most frequent variant followed by c.1021C>T found in Crigler-Najjar syndrome type 1 patients. The evaluation of promoter polymorphism A(TA)_nTAA in the affected children and their families further supported the body of evidence that the A(TA)₇TAA allele could enhance the effect of other structural variants in Crigler-Najjar syndrome patients. To our knowledge, this is the first comprehensive study on molecular genetics of persistent unconjugated hyperbilirubinemias from Pakistan. This study expands the spectrum of UGT1A1 variants and should help in improved clinical diagnosis, genetic counseling and prenatal diagnosis of the affected families.