?Cold? single-strand conformational variants for mutation analysis of the RET protooncogene*1, *2

Background. RET protooncogene mutation analysis is a routinely performed predictive DNA test in kindreds affected by multiple endocrine neoplasia (MEN) types 2A and 2B and familial medullary thyroid carcinoma (FMTC) and is a valuable diagnostic tool in newly diagnosed cases of medullary thyroid carcinoma (MTC). Methods. We tested the suitability of the recently introduced "cold" single-stand conformational variant (SSCV) technique, which promises rapid simple, nonradioactive detection of sequence variants in the identification of germline and somatic RET mutations. A total of II different mutations in exon 10 (codons 609, 611, 628, and 620) and 6 mutations in exon 11 (codon 634) were studied. Results. Conditions were optimized so that conformational variants were demonstrated for all mutations examined in a single setting for exons 10 and 11. A novel six base pair (bp) inframe deletion between cysteines 630 and 634 was detected in a sporadic MTC. This adds to the evidence that not only cysteine deletions and substitutions but also changes in the spacing between cysteine residues have a pathogenic effect. Conclusions. Our results indicate that the cold SSCV method offers the advantages of simplicity, time savings, and nonradioactive detection for screening for RET sequence variants in hereditary and sporadic MTCs.