Immunodeficiency associated with a deletion in the short arm of the X-chromosome

The immunocapacity of a 28-year-old mentally retarded proband and her clinically normal mother and sister, all having a deletion of the short arm of one of the X-chromosomes [46, X, del (X) (pter to 22: :p11 to qter)], was evaluated. The concentrations of immunoglobulin IgA (0 . 4 g/l), IgG (4 . 4 g/l) and IgM (0 . 2 g/l) were low in the proband. The serum IgA (0 . 9 g/l) concentration of her mother was also at the lower normal limit. The serum concentration of complement component C4 was low both in the proband (0 . 17g/l) and in her mother (0 . 18 g/l). Phagocytosis and killing of bacteria by granulocytes were normal in all of them. However, the chemotactic response of granulocytes was at the lower normal level in the patient. The in vitro responses of peripheral blood lymphocytes to the polyclonal T-clonal mitogens, PHA and Con A, were about half normal in the patient and were also decreased in her mother. The response was also decreased against PWM, to about one-sixth of the normal value in the patient and to one-half in her mother. The Con A response was decreased in the sister, while her PHA and PWM responses were normal. In contrast to these findings, the responses against the antigen-specific stimulators, PPD and oidiomycin, were normal in all subjects. Natural killer cell activity against the K-562 cell line was decreased in the patient but normal in her mother and sister. The number of B cells was at the normal limit in all subjects. The amount of E rosette-forming T lymphocytes was normal but the amount of ANAE-positive cells was decreased, especially in the proband (31%). Our results describe a new human immunodeficiency state, probably associated with X-chromosome deletion. We suggest that the short arm of the X-chromosome exerts its effect on regulatory T cells. Whether the humoral defect is connected with suppressor T cells remains to be established.