Segregation analysis of susceptibility/resistance to periportal fibrosis in Schistosoma mansoni infections in endemic area [Umzoukra village - Gezira State - Sudan]

We carried out segregation analysis of susceptibility to periportal fibrosis caused by Shistosoma mansoni. A regressive logistic model of the disease was applied to 42 pedigrees ascertained during screening of one the infection endemic area of Sudan. The affected status was defined as a presence of the fibrosis irrespectively to severity of injury. Transmission probability model indicated a significant contribution of a major gene in the control of the pathology. The susceptibility to periportal fibrosis could be described within the framework of a recessive major gene diallele model, assuming incomplete age and squared-age dependent penetrance of genotypes. According to this model, the disease was manifested in almost all homozygous carriers of the mutant allele, while the risk of the disease for normal homozygotes and heterozygotes did not exceed 0.31. The frequency of disease allele in the population studied was estimated as 0.59. We also found non-majorgene phenotypic correlations between parents and offspring in the incidence of periportal fibrosis caused by Schistosoma mansoni