Background: Human ficolin-2 (L-ficolins) encoded by the FCN2 gene are pattern-recognition proteins involved in innate immunity and are associated with several infectious diseases.
Methods: A Nigerian cohort of 168 Schistosoma haematobium-infected individuals and 192 healthy controls were examined for functional single-nucleotide polymorphisms in the promoter region (-986G>A, -602G>A, -4A>G) and in exon 8 (+6424G>T) using real-time polymerase chain reaction.
Results: The FCN2 -986A and -4G alleles were significantly associated with the occurrence of schistosomiasis (P = .0004 for -986G>A; P = .0001 for -4A>G). The heterozygous genotypes (P = .0006 for -986G>A; P = .0002 for -4A>G) were observed to be a risk factor for susceptibility to schistosomiasis, whereas the homozygous genotypes of major alleles (P = .0002 for -986G>A; P = .0001 for -4A>G) were observed to shield against schistosomiasis. The haplotype AGGG (P = .0002) was observed to be a risk factor for susceptibility to schistosomiasis compared with controls, and the haplotype GGAG (P = .04) was observed to confer protection compared with patients. Ficolin-2 serum level was significantly higher in controls (P < .005) and in controls with GGAG haplotypes (P < .0001).
Conclusions: Our findings demonstrate that FCN2 promoter variants (-986G>A and -4A>G) influence ficolin-2 serum levels and susceptibility to schistosomiasis.