AGAMMAGLOBULINEMIA IN A GIRL WITH A MOSAIC OF RING-18 CHROMOSOME

A patient with a mosaic karyotype 45,XX,-18/46,XX,dic r(18)/46,XX,r(18 ) with multiple phenotypic abnormalities and immunodeficiency was pres ented at the age of 14 years. Immunological investigation revealed mar kedly decreased IgG, IgA and in two of three evaluations also IgM leve ls. Although selective IgA deficiency is frequent in patients with a r ing chromosome 18, this is the third patient described with decreased levels of other immunoglobulin isotypes. The association of chromosome 18 partial deletions and immunoglobulin abnormalities suggests the pr esence of an as yet unrecognised gene with a pivotal role for immunogl obulin production on chromosome 18.