Immunological and genetic analysis. (A) The patient presented with persistently low numbers of CD4⁺ T-cells and elevated numbers of CD8⁺ T-cells throughout a period of 7 years. (B) Homozygosity mapping identified several homozygous regions. ITK (asterisk) was located inside a homozygous region on chromosome 5. (C) Identification of a homozygous nonsense mutation (c.C49T:p.Q17X) in the gene ITK. (D) The index patient shows complete absence of TCRVα24⁺/TCRVβ11⁺ iNKT-cells.