Consanguinity is not the only factor influencing the occurrence of autosomal recessive disorders such as familial Mediterranean fever (FMF). The extended, multiple consanguineous Turkish pedigree presented here demonstrates that the population frequency of certain mutations (so-called "ancient" mutations) can be at least equally important. In high-risk populations different combinations of mutations can occur within the same family, increasing not only the intrafamilial clinical variability, but also causing considerable recurrence risks even in marriages with unrelated spouses.