RET and achondroplasia: However, these size and frequency characteristics do not match the expectation of mutational clones previously described by DNA studies of Apert, Men2B and achondroplasia mutations, which, based on the number of mutant molecules quantified in each clustered set of testis pieces, could involve anything from ∼100 (the lower limit of detection) to over 1 million cells [20], [21], [22], [24].