Defective monocyte phagocytic function as a possible genetic marker for heumatic susceptibility

The activity of the monocyte phagocytic system in children with rheumatic heart disease [RHD], their parents, their normal siblings and in nonrheumatic families was investigated. Phagocytic activity of isolated monocytes was assessed using luminol-dependent chemiluminescence. The count per minute of emitted light was measured before and after stimulation with zymosan solution. The results indicate that one-third of the siblings of children with RHD were genetically free while two-thirds, as well as the parents, were heterozygous, and that children with RHD were homozygous for [a] mutant gene[s] responsible for the defective function of the monocyte phagocytic system. The findings are strongly suggestive of autosomal recessive inheritance