Persistent Ascites Revealing Mendelian Susceptibility to Mycobacterial Disease Due to Il-12Rβ1 Deficiency: A Case Report and Review of the Literature Publisher



Dolikhani M ; Shakibamaram G ; Rashtian P ; Saberi M ; Reshadmanesh A ; Ghafaripour H ; Moradian E ; Mahdaviani S A ; Bustamante J
Source: Case Reports in Immunology Published:2026

Abstract

Background: Mendelian susceptibility to mycobacterial disease (MSMD) is a subset of inborn errors of immunity (IEIs) predisposing to clinical infections from less virulent mycobacterial species. Variants in 22 genes, particularly in IL-12Rβ1, have been identified that impair interferon-gamma (IFN-γ)-mediated immunity. We report a new rare MSMD patient with a homozygous IL12RB1 variant who presented with severe and persistent ascites. Case Report: We investigated a 30-month-old girl who developed an abscess and lymphadenopathy (LAP) in the left axilla after receiving a BCG vaccine. She was diagnosed and treated for BCG-osis. She presented with ascites, which gradually worsened, along with symptoms of liver dysfunction. Her portal hypertension (PHT) was considered the most likely cause of ascites after exclusion of other common causes. The whole exome sequencing (WES) revealed a homozygous rare variant (c.635G>A; p.Arg212Gln) in the IL12RB1 gene. Sanger sequencing analysis confirmed that both parents were heterozygous carriers of the variant. She made a good recovery after receiving the appropriate antimycobacterial and ascites treatments, with significant resolution of her symptoms. Because disseminated M. bovis BCG infection occurred in the setting of IL-12Rβ1 deficiency, prolonged susceptibility-guided antimycobacterial therapy with adjunctive IFN-γ1b and close follow-up by infectious disease and immunology, was planned. Conclusion: This case highlights severe persistent ascites as an unusual manifestation of PHT in IL-12Rβ1 deficiency associated with MSMD. Evaluation for PHT should be considered in MSMD patients with abdominal distension, gastrointestinal symptoms, hepatosplenomegaly, abnormal liver function tests, growth failure, or unexplained free abdominal fluid. Copyright © 2026 Mohammadreza Dolikhani et al. Case Reports in Immunology published by John Wiley & Sons Ltd.