BCL10 loss-of-function novel mutation leading to atypical severe combined immunodeficiency.

Background: Severe combined immunodeficiency (SCID) is characterized by severe, early-onset infection in infants. B-cell lymphoma/leukemia (BCL) 10 defects causing SCID have been reported previously in two patients.

Material & Methods: A seven-month-old female infant was admitted with bilateral pneumonia requiring ventilatory support. She had a history of recurrent infections starting from four months of age. The patient was investigated for primary immunodeficiency.

Results: Immunological investigations revealed hypogammaglobulinemia with normal CD4 and CD8 lymphocyte counts, while a lymphocyte proliferation assay showed absent response to phytohemagglutinin stimulation, thereby establishing the diagnosis of an atypical form of SCID. Genetic testing revealed a homozygous mutation in the BCL10 gene, with both parents demonstrating a heterozygous state (NM_003921.5:c.271A > C:p.[Thr91Pro]). The patient died before bone marrow transplantation due to severe disseminated adenovirus disease.

Conclusion: We report the first patient from the Middle East with a novel homozygous mutation in the BCL10 gene causing SCID.