Uridine monophosphate kinase and susceptibility to invasive Haemophilus influenzae type B disease.

A polymorphic genetic variant of the pyrimidine pathway enzyme, uridine monophosphate kinase-3 (UMPK-3), was positively associated with invasive Hib disease. All UMPK 3-3 homozygotes in this study were Hib cases, and we found that in cases and controls, there was no difference between UMPK phenotype and serum levels of total Hib antibody as measured by radioimmunoassay. This suggests that UMPK-3 may play a role in mediating the non-humoral immunity to Hib. However, unlike other enzyme variants in the nucleoside synthesis pathways which result in syndromes of severe immunodeficiency, this gene appears to confer a more subtle disease susceptibility. Thus, the UMPK-3 allele, although rare in Caucasians, is associated with an increased risk of invasive Hib infection in Alaskan Eskimos.