The complement component C4 in sudden infant death

The aim of the present study was to compare partial deletions of the comple ment C4 gene in victims of totally unexplained sudden infant death (SID) (n = 89) and borderline SID (n = 15) with and without slight infections prior to death, in cases of infectious death (n = 19), and in living infants wit h and without infections (n = 84), The SID and borderline SID groups were p ooled, In this total SID group slight infections prior to death was associa ted with deletion of either the C4A or the C4B gene (P = 0.033), and the SI D victims with such infections had a higher deletion frequency than the con trols (P = 0.039). There were no differences between the living infants wit h and without upper airway infections. Conclusion The present study confirms that partial deletions of the C4 gene in combination with slight upper airway infections may be a risk factor in sudden infant death.