ABSTRACT
Severe combined immunodeficiency (SCID; B) causes defects in both T cells and B cells. The most common subtypes can be categorized into an X-linked disease (mutation of IL-2 receptor) or an autosomal recessive condition (mutation of adenosine deaminase gene which leads to a build-up of toxins and hence compromised proliferation of lymphocytes). Characteristically, there is hypoplasia and atrophy of the thymus and mucosa-associated lymphoid tissue (MALT). Clinical features include diarrhoea, failure to thrive and skin disease (graft-versus-host induced, secondary to transplacental maternal T cells or blood transfusion-related caused by donor T cells).
