Objective: Dubin-Johnson syndrome (DJS) is a hereditary liver disease caused by biallelic pathogenic variants in the ABCC2 gene. As a rare disease, the ABCC2 genotype and clinical phenotype characteristics of DJS patients still need to be summarized in depth.

Methods: Nine cases diagnosed with DJS and treated in the Department of Pediatrics of the First Affiliated Hospital of Jinan University were collected as the study subjects. Clinical and laboratory data, general information, symptoms, signs, pathological changes, treatment, and prognostic conditions were systematically analyzed. Targeted high-throughput sequencing was used to detect hereditary diseases. The positive results for the family lineage were verified by Sanger sequencing. The pathogenicity of the novel ABCC2 variants was evaluated according to the American College of Medical Genetics and Genomics guidelines and standards. One-way analysis of variance or Kruskal-Wallis test was used to compare the statistical differences between multiple groups of data.

Results: Among the nine DJS cases, seven and two were males, and females. All of them had the initial symptom of jaundice (100%), with a median age of onset of 5 (2,15) days. During the course of the disease, seven (7/9) and two (2/9) cases had hepatomegaly and splenomegaly. All of the patients exhibited direct hyperbilirubinemia, concurrently with elevated total bile acids (TBA) and γ-glutamyl transferase (GGT). Serum transaminases (4/9) and alkaline phosphatase levels (3/9) were elevated in some patients. A total of twelve types of ABCC2 variants were detected in nine cases, of which c.2362_2363del (p.Leu788ValfsTer13), c.364C>T (p.Gln122Ter), c.338T>C (p.Leu113Pro) and c.419T>A (p.Ile140Lys) were novel pathogenic/likely pathogenic variants. Jaundice disappeared and alleviated in five cases (5/9) and four cases (4/9), while hepatomegaly improved in five cases (5/9) at the last follow-up at 7.79 (7.0,15.25) months following treatment with drugs such as liver protectives, choleretics, and jaundice-reducing agents. Among them, three cases (3/9) had a normal restored liver size. All patients had varying degrees of improvement in bilirubin, TBA, GGT, and ALP levels.

Conclusions: The onset of high GGT cholestatic jaundice is the main clinical manifestation in patients with neonatal DJS. The genetic analysis results showed four novel types of variants, which expanded the ABCC2 gene variation spectrum, providing novel molecular markers for confirming a diagnosis of DJS. The patient's clinical manifestations and laboratory abnormalities improved or disappeared after internal medicine treatment, suggesting that DJS may be a type of genetic disease with a favorable long-term prognosis.