Combined Immunodeficiency Associated With <scp>MAP2K1</scp> p. <scp>Tyr130His</scp> Variant in Cardiofaciocutaneous Syndrome: A Case Report With Literature‐Based Phenotypic Comparison

Cardiofaciocutaneous syndrome (CFCS) is a RASopathy involving craniofacial, cardiac, cutaneous, and neurologic features. MAP2K1 mutations, particularly in the kinase domain, are linked to CFCS type 3. Immune dysfunction has not previously been reported with the p.Tyr130His variant. To describe the case of combined immunodeficiency (CID) associated with the MAP2K1 p.Tyr130His variant. A 4-month-old female with CFCS presented with recurrent infections, growth failure, and ectodermal findings. Immunologic workup revealed hypogammaglobulinemia, low T cell subsets, and absent vaccine responses. Genetic analysis identified the MAP2K1 p.Tyr130His variant. She was started on intravenous immunoglobulin and prophylaxis, with clinical improvement. We describe a case of CID associated with the MAP2K1 p.Tyr130His variant adding to the growing evidence of immune dysregulation in CFCS.