Figure 2.

No RET ATA-B, C or D alleles were found in the ESP control databases. Only one instance of the V804M allele (ATA-A) was found among the 13 000 sequenced alleles, indicating a very low frequency of bona fide MTC-related RET mutations in healthy individuals. In contrast, 15 alleles of Y791F were found within the ESP control databases, indicating that the frequencies of this specific variant behave differently, possibly as an accompanying genetic modifier or as a benign polymorphism.