IL2RG: A series of three novel mutations with clinical manifestations

Abstract

Background: X-linked severe combined immunodeficiency (SCID) is caused by mutations in the IL2RG gene and classically presents with absent T cells and natural killer (NK) cells. Mutational analysis has contributed to the understanding of this gene. Methods: The primary immunodeficiency (PID) registry was reviewed for patients with SCID with novel IL2RG mutations. The clinical phenotype was assessed using a retrospective chart review. Results: We describe 3 novel mutations in the IL2RG. The first was a guanine to adenine substitution at position 215 (c.215 G > A) in exon 2 leading to a cysteine to tyrosine substitution at position 72 (p.Cys72Tyr), with a typical T− B+ NK− phenotype. The second was a deletion of thymine at position 618 and adenine at position 619 (c.618_619TA) in exon 5, leading to a frameshift at the 206 amino acid (p.His206fs). The phenotype was characterized by a classic SCID presentation and immunophenotyping revealed a low number of absolute lymphocytes with mostly B cells, low levels of immunoglobulins, as well as very low NK cells. Finally, the third mutation was a guanine to cytosine substitution at position 341 (c.341 G > C) in exon 3 leading to a glycine to alanine substitution at position 114 (p.Gly114Ala), presenting with a T+ B+ NK+ phenotype. The presence of T and NK cells in IL2RG are discussed in the context of other mutations allowing for T and NK cells in IL2RG mutations, as well as in the setting of maternal engraftment. Conclusion: To the best of our knowledge we describe 3 novel mutations in the IL2RG gene and the associated phenotypes. These mutations illustrate that these patients can have atypical immunological evaluations. Statement of novelty: To the best of our knowledge, this paper describes 3 novel mutations in the IL2RG gene.