In 10 (24.4%) out of 41 patients with MTC (in groups 1 and 2 pooled into a single array), the basal calcitonin level lay within the “gray zone” from 10 to 100 pg/mL; 51.9 (24.6–59.9); minimum, 13 pg/mL; maximum, 98 pg/mL. The gene discussed is CALCA; the disease is medullary thyroid gland carcinoma.