TNFRSF1A and TNF receptor 1-associated periodic fever syndrome: In TRAPS patients, the interpretation of TNFRSF1A mutations might be challenging: for instance, P46L substitution occurs in up to 20% of clinically asymptomatic West African individuals, which suggests that it represents a polymorphism rather than a disease-causing mutation, and R92Q substitution, relatively common in the Caucasian population, is a low-penetrance variant, which could have a weak contribution to disease expression.