Is there a genetic immune defect in families with meningococcal meningitis?

Abstract

Summary The greatly increased risk of contracting meningococcal meningitis in family contacts of patients may be due to genetic susceptibility to this disease. To test this postulate the distribution of HLA, Gm, Am and Km allotypes was analysed in nine families with multiple cases of meningococcal meningitis and these findings were linked to the response to vaccination with group C meningococcal polysaccharides. Pedigree analysis using these markers showed no genetic predisposition to the disease: haplo- and allotypes were randomly distributed between affected and non-affected sibs. There was no significant difference in immune response between patients, their sibs and more distantly related children and the magnitude of response could not be linked to heterozygosity of Gm-Am haplotypes or the presence or absence of the Km 1 positive allotype. C4, C3, factor B and total haemolytic and alternative pathway complement function were measured in three families but no deficiencies were found. We conclude that among our patients there is no obvious genetically linked immune defect which increases their susceptibility to meningococcal meningitis.