2. Academic Validation
  3. Low-GGT intrahepatic cholestasis associated with biallelic USP53 variants: Clinical, histological and ultrastructural characterization

Low-GGT intrahepatic cholestasis associated with biallelic USP53 variants: Clinical, histological and ultrastructural characterization

  • Liver Int. 2020 May;40(5):1142-1150. doi: 10.1111/liv.14422.
Jing Zhang 1 2 3,  Ye Yang 1 2 3,  Jing-Yu Gong 1,  Li-Ting Li 2 3,  Jia-Qi Li 1,  Mei-Hong Zhang 1,  Yi Lu 2 3,  Xin-Bao Xie 2 3,  Yu-Ren Hong 4,  Zhang Yu 4,  A S Knisely 5,  Jian-She Wang 2 3
Affiliations

Affiliations

  • 1 The Department of Paediatrics, Jinshan Hospital, Fudan University, Shanghai, China.
  • 2 The Center for Paediatric Liver Diseases, Children's Hospital of Fudan University, Shanghai, China.
  • 3 Department of Paediatrics, Shanghai Medical College of Fudan University, Shanghai, China.
  • 4 Electron Microscopy Core Laboratory, Shanghai Medical College, Fudan University, Shanghai, China.
  • 5 Institut für Pathologie, Medizinische Universität Graz, Graz, Austria.
PMID: 32124521 DOI: 10.1111/liv.14422
Abstract

Background & aims: In about 20% of children with cholestasis and normal or low serum gamma-glutamyltransferase (GGT) activity, no aetiology is identified. We sought new genes implicated in paediatric hepatobiliary disease.

Methods: We conducted whole-exome sequencing in 69 children evaluated at our centre from 2011 to 2018 who had low-GGT cholestasis and in whom homozygous/compound heterozygous predictedly pathogenic variants (PPVs) in ATP8B1, ABCB11, NR1H4, MYO5B or TJP2 were not found. Clinical records and findings on LIGHT microscopy and transmission electron microscopy of liver biopsy Materials were reviewed.

Results: In seven patients from seven unrelated families, biallelic PPVs (10 in total) were found in USP53, recently associated with intrahepatic cholestasis. Seven variants were classified as pathogenic: one canonical splicing, c.569 + 2T > C, and six nonsense or frameshifting: c.169C > T (p.Arg57Ter), c.581delA (p.Arg195GlufsTer38), c.831_832insAG (p.Val279GlufsTer16), c.1012C > T (p.Arg338Ter), c.1426C > T (p.Arg476Ter) and c.1558C > T (p.Arg520Ter). Three were likely pathogenic: c.297G > T (p.Arg99Ser), c.395A > G (p.His132Arg) and c.878G > T (p.Gly293Val). In all patients, jaundice began at age <7 months. Cholestasis was transient, with documented resolution of hyperbilirubinaemia in all (oldest patient now aged 5 years) except one, who was lost to follow-up. LIGHT microscopy identified intralobular cholestasis, giant-cell change of hepatocytes and perisinusoidal-perihepatocytic and portal-tract fibrosis. Ultrastructural study revealed elongated hepatocyte-hepatocyte tight junctions. One patient was deaf.

Conclusion: USP53 interacts with the tight junction constituent TJP2. TJP2 mutation can cause low-GGT intrahepatic cholestasis, with elongated hepatocyte-hepatocyte tight junctions, as well as deafness. Our findings extend a preliminary report of USP53 disease and indicate that USP53 mutation may generate a partial phenocopy of TJP2 disease.

Keywords

TJP2; USP53; deafness; low gamma-glutamyltransferase cholestasis; transmission electron microscopy.

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