A 55-year-old man with MEN2A undergoes prophylactic total thyroidectomy. Genetic testing shows RET codon 634 mutation (exon 11). According to ATA risk categories for hereditary MTC, this mutation is classified as:

• A Moderate risk — thyroidectomy recommended by age 5 years
• B Highest risk — thyroidectomy recommended within first months of life
• C High risk — thyroidectomy recommended in first 6 months of life ✓
• D Low risk — annual calcitonin monitoring is acceptable

Explanation

ATA classifies RET mutations for MTC risk: Highest risk (codon 918/M918T, MEN2B) requires thyroidectomy within first 6 months. High risk (codons 634, 633, 631, exon 11 mutations including C634R/F/G/S/W/Y, C620R, C618R) is associated with MEN2A and requires prophylactic thyroidectomy within first 6 months to 5 years depending on calcitonin level. Moderate risk mutations (codons 609, 611, 618, 620, 630, 768, 790, 791, 804, 891, 912) recommend thyroidectomy by age 5. Codon 634 falls in the high-risk category.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.