The authors of the above study, published last spring in Frontiers in Zoology, examined fecal samples collected from a wild population of red-fronted lemurs (Eulemur fulvus rufus) in western Madagascar to better determine the association of IL4-gene promoter polymorphisms with nematode infections and the possible functional role of the IL4-polymorphism on male reproductive success. Sequence analysis of lemur DNA showed a new SNP in the IL4 gene promoter area. Out of the three genotype--T/T, C/T and C/C--the genotype T/T showed higher rates of nematode infection intensities (see graph above). Yet, genetic population analyses collected over a period of ten years suggested a higher overall reproductive success of T/T males than expected. Results suggest that the intensity of parasite infections is linked to the regulatory effect of an IL4 gene promoter polymorphism. Despite limits of the study, such as low frequencies of T/T genotypes, Clough et al. assert that the IL4 polymorphism contributes to a better understanding of the immune response in red-fronted lemurs against gastro-intestinal parasites.