Following the isolation of CGRP from patients with medullary thyroid carcinoma (MTC) (Morris et al., 1984), the peptide was, together with calcitonin, found to be expressed in the majority of MTCs and released into the circulation (Schifter et al., 1986; Takami et al., 1990; Hanna et al., 1997). This evidence concerns the gene CALCA and medullary thyroid gland carcinoma.