<prompt> Regarding severe combined immunodeficiency disease SCID, which of the following statements is true?Adenosine deaminase deficiencyMyeloperoxidase deficiencyNADPH oxidase deficiencyC1 esterase deficiency  <response>: Severe combined immunodeficiency SCID Represents a constellation of genetically distinct syndromes, all having in common defects in both humoral and cell-mediated immune responses. The most common form is X-linked 50 to 60 of cases and hence SCID is more common in boys than in girls. The genetic defect in the X-linked form is a mutation in the common g-chain gc subunit of cytokine receptors. T-cell numbers are greatly reduced, and although B cells may be normal in number, antibody synthesis is impaired. The remaining cases of SCID are inherited as autosomal recessive. The most common cause of autosomal recessive SCID is a deficiency of the enzyme adenosine deaminase ADA.There may be greater reduction in the number of T lymphocytes than of B lymphocytes. 