Recurrent infections in partial complement factor I deficiency: evaluation of three generations of a Brazilian family

Abstract

SummaryWe report here on the evaluation of a factor I-deficient Brazilian family (three generations, 39 members) with strong consanguinity. The complete factor Ideficient patients ( n = = = = 3) presented recurrent respiratory infections, skin infections and meningitis; one of them died after sepsis. They presented an impaired total haemolytic activity (CH 50 ), low C3, low factor H and undetectable C3dg/C3d. Partial factor I deficiency was detected in 16 family members (normal low cut-off value was 25 μ μ μ μ g/ml). Respiratory infections were the most common clinical occurrence among partial factor I-deficient relatives. Two of them were submitted to nephrectomy following recurrent urinary tract infections. An additional two heterozygous relatives presented with arthritis and rheumatic fever. Apparently, patients with partial factor I deficiency are also at higher risk for recurrent infections. Vaccination against capsulated bacteria and the eventual use of prophylactic antibiotics should be considered individually in this patient group.

Characteristics of the complement system gene expression deficiency in patients with symptomatic pulmonary embolism

“…However, in our present study, it is unclear whether the cause of the up-regulation of CD55 and CD59 mRNAs is inherited or acquired. It has been reported that Factor I deficiency was associated with recurrent bacterial infections [18]. In our present study, Factor I mRNA expression was down-regulated in PE patients compared with controls, suggesting that PE patients are susceptible to bacterial infections.…”

Genetic, molecular and functional analyses of complement factor I deficiency

“…Several cases of near complete FI deficiencies have been reported and were found to lead to systemic consumption of C3, factor H (FH) and factor B (FB) due to uninhibited activation of the alternative pathway. Because of this consumption, opsonization with C3b cannot occur and patients are much more susceptible to recurrent pyogenic infections, such as otitis media, pneumonia and meningitis 1–4. There have also been reports of FI‐deficient patients who suffer from glomerulonephritis 5 or systemic lupus erythematosus (SLE) 6.…”

“…To date, only three studies have identified a molecular defect in FI at the DNA level in patients with a full FI deficiency 7–9. The remainder of the literature comprises reports of clinical presentation 1–6, 10, 11. The mutant FI proteins in question have not yet been expressed in a recombinant form and therefore there is no information available concerning the effects of these mutations on FI secretion and function.…”

Local complement activation in aqueous humor in patients with age-related macular degeneration

“…C3, FH, 15 FI, 16 and sC5b-9 17 were measured by ELISA as previously described. C3a (Progen, Heidelberg, Germany) and Ba (Quidel, San Diego, CA, USA) were measured by ELISA following the manufacturer's protocols.…”