Alarcon et al. (1988) described 2 brothers who had a low expression of antigen receptor on the surface of their T lymphocytes. Functional analyses of their T cells showed impaired immune response to alloantigens, tetanus toxoid, and mitogens. ... Alarcon et al. (1988) described 2 brothers who had a low expression of antigen receptor on the surface of their T lymphocytes. Functional analyses of their T cells showed impaired immune response to alloantigens, tetanus toxoid, and mitogens. Biochemical studies showed reduced intracellular expression of CD3-zeta chains; all other components of the T-cell receptor-CD3 complex were expressed normally. Alarcon et al. (1988) suggested that the impaired association of the CD3-zeta chain with the other chains of the complex was the primary defect leading to the low expression of T-cell receptor-CD3 complex and immunodeficiency in these children. Failure to thrive had been diagnosed in the proband at 11 months; subsequently, chronic anorexia, diarrhea, and recurrent episodes of bronchopneumonia were noted. The diarrhea was shown to be associated with a malabsorption syndrome, which was unresponsive to a gluten-free diet. Biopsy of the small bowel showed absence of villi; however, the patient was negative for HLA-DR3 and -DR7. The boy died of severe autoimmune hemolytic anemia at the age of 3 years. The patient's brother had required hospital admission for respiratory infection, but on the whole was much more mildly affected than his brother. Rieux-Laucat et al. (2006) described a boy, of Caribbean origin and of unknown paternity, with primary T-cell immunodeficiency. He presented at the age of 4 months with erythroderma, protracted diarrhea, and pulmonary abscesses caused by Pseudomonas aeruginosa. During the next 2 years, he had recurrent episodes of herpes simplex virus infection of the mouth and skin, 2 episodes of oral and skin infections with Candida albicans, and 2 pulmonary infections. The patient's T-cell counts were very low, B-cell counts were normal, and there was eosinophilia. A haploidentical bone marrow transplantation, with the mother as the donor, was performed when the patient was 30 months old. The transplant resulted in sustained donor-recipient chimerism and correction of the immunodeficiency. Three years later, the patient was well and living at home.
In a boy with primary T-cell immunodeficiency, Rieux-Laucat et al. (2006) identified homozygosity for a germline Q70X mutation in the CD247 gene (186780.0001). Some of the patient's T cells had low levels of the T-cell receptor-CD3 complex and ... In a boy with primary T-cell immunodeficiency, Rieux-Laucat et al. (2006) identified homozygosity for a germline Q70X mutation in the CD247 gene (186780.0001). Some of the patient's T cells had low levels of the T-cell receptor-CD3 complex and carried the Q70X mutation on both alleles of the CD3Z gene, whereas other T cells had normal levels of the complex and bore the Q70X mutation on only 1 allele of CD3Z, plus 1 of 3 heterozygous somatic mutations of CD3Z on the other allele (186780.0002-186780.0004), allowing expression of poorly functional T-cell receptor-CD3 complexes. Thus the patient had both inherited and somatic CD3Z mutations as the basis of the T-cell deficiency.