{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,24]],"date-time":"2026-08-24T15:19:02Z","timestamp":1787584742378,"version":"build-2736575974"},"reference-count":36,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2025,11,25]],"date-time":"2025-11-25T00:00:00Z","timestamp":1764028800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Immunol."],"abstract":"<jats:p>\n                    Major histocompatibility complex class II (MHC II) deficiency (bare lymphocyte syndrome type II) is an autosomal-recessive combined immunodeficiency caused by pathogenic variants in the transcriptional regulators CIITA, RFXANK, RFX5, or RFXAP. While RFXANK founder mutations predominate in North Africa, CIITA-related disease is extremely rare. We report two siblings from a consanguineous Moroccan family with the classic early-infancy phenotype. The elder sister developed recurrent febrile rashes, oral candidiasis, and locoregional BCGitis with acid-fast bacilli in granulomas, followed by progressive respiratory failure and fatal cytomegalovirus pneumonitis despite antiviral therapy; immunology showed profound CD4\n                    <jats:sup>+<\/jats:sup>\n                    lymphopenia with CD4\/CD8 inversion, near-absent HLA-DR on B cells, undetectable IgG\/IgA, and elevated IgM. The proband, identified during family follow-up, had recurrent mucocutaneous infections, marked CD4\n                    <jats:sup>+<\/jats:sup>\n                    lymphopenia with CD4\/CD8 inversion, and near-absent HLA-DR on B cells; he was started on monthly intravenous immunoglobulin and trimethoprim\u2013sulfamethoxazole prophylaxis. Targeted next-generation sequencing revealed a novel homozygous nonsense CIITA variant (c.1615C&amp;gt;T; p.R539*), predicted to truncate the GTP-binding domain, abolish downstream leucine-rich repeats, and undergo nonsense-mediated decay, and classified as pathogenic according to ACMG criteria. Molecular confirmation enabled genetic counseling, cascade testing, withholding BCG, and urgent evaluation for allogeneic hematopoietic stem-cell transplantation. This case, likely the first CIITA-related MHC II deficiency reported from Morocco, expands the regional genotypic spectrum and underscores the value of early HLA-DR flow-cytometric assessment and prompt molecular testing in infants from consanguineous families to guide prophylaxis, vaccination decisions, and timely referral for curative therapy.\n                  <\/jats:p>","DOI":"10.3389\/fimmu.2025.1707772","type":"journal-article","created":{"date-parts":[[2025,11,25]],"date-time":"2025-11-25T05:11:28Z","timestamp":1764047488000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":2,"title":["Case Report: A novel CIITA mutation causing MHC class II deficiency: first reported case in Morocco"],"prefix":"10.3389","volume":"16","author":[{"given":"Aziza Bachir","family":"Kattra","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fatima","family":"Ailal","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ibtihal","family":"Benhsaien","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mohammed","family":"Fahi","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Asmaa","family":"Drissi 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