[Clinical features and genetic analysis of a child with Progressive familial intrahepatic cholestasis type 8 due to compound heterozygous variants of KIF12 gene].

OBJECTIVE

To explore the clinical phenotype and genetic characteristics of a child with Progressive familial intrahepatic cholestasis type 8 (PFIC8). METHODS A child with PFIC diagnosed at Beijing Children's Hospital Affiliated to Capital Medical University in September 2025 was selected as the study subject. Peripheral venous blood samples were collected from the child and her parents. Following extraction of genomic DNA, whole-exome sequencing (WES) was carried out. Candidate variants were validated by Sanger sequencing. The pathogenicity of the candidate variants was classified based on the guidelines from American College of Medical Genetics and Genomics (ACMG). This study was approved by the Medical Ethics Committee of Beijing Children's Hospital Affiliated to Capital Medical University (Ethics No.: 2023-E-126-Y).

RESULTS

The proband, a 2-month-old female infant, had manifested jaundice of the skin and sclera, and slightly distended abdomen. She had no visible abdominal wall varicose veins, soft abdomen, and no palpable masses. Biliary atresia was ruled out by intraoperative cholangiography. WES revealed that she has harbored compound heterozygous variants of KIF12 gene, namely c.809C>T (p.Ala270Val) and c.1313G>A (p.Arg438Lys), which were verified by Sanger sequencing to have derived from her mother and father, respectively. According to the ACMG guidelines, both variants were classified as variants of uncertain significance (VUS). Based on the pre-defined search strategy, 10 articles were retrieved, which involved 25 PFIC cases, including 5 from China. Together with the proband of this study, the 26 PFIC patients have primarily presented with high GGT cholestasis, with the genetic cause in all cases attributed to variants of the KIF12 gene.

CONCLUSION

The c.809C>T and c.1313G>A compound heterozygous variants of the KIF12 gene probably underlay the pathogenesis of cholestatic liver disease in this child. Above findings have enriched the mutational and phenotypic spectra of PFIC8.