MANNOSE-BINDING PROTEIN GENE-MUTATIONS ASSOCIATED WITH UNUSUAL AND SEVERE INFECTIONS IN ADULTS

A defect in opsonisation can cause a common immunodeficiency. A mutati on in mannose binding protein (MBP) caused by point mutations in the M BP gene will lead to such a defect, This type of syndrome can cause re current infections in infants between 6 and 18 months of age but is no t generally believed to predispose to adult infections. We looked at 4 patients with severe and unusual infections in whom MBP gene mutation s were the only identified cause of immunodeficiency and one patient w ith combined MBP and IgA deficiency, We analysed the MBP genotypes of all the patients in whom we suspected an immunodeficiency because of t heir clinical history. Infections seen were recurrent skin abscesses, chronic cryptosporidial diarrhoea, meningococcal meningitis with recur rent herpes simplex, and fatal klebsiella lobar pneumonia. Both sexes were affected and ages ranged from 15 to 56 years. Two patients were h omozygous for codon 54 mutations, one patient bad codon 52 and codon 5 4 mutations and was phenotypically homozygous, and two patients were h eterozygous for codon 54 mutations. Individuals homozygous for MBP mut ations are unusual in the general population (approximate frequency 0. 3%).The occurrence of three homozygotes for MBP mutations among these five infected patients suggests that MBP deficiency may confer a life- long risk of infection.