[Genotype-phenotype correlations in multiple endocrine neoplasia type 2]

To evaluate the relationship between different RET mutations and the aggressiveness of hereditary medullary thyroid cancer (HMTC) or the presentation of other endocrine disorders in patients with multiple endocrine neoplasia type 2 (MEN2).

A total of 73 thyroid medullary carcinoma patients from 22 Chinese kindreds who were treated in our center from 2010 to 2015 were enrolled. RET genes in the patients and their relatives were screened.

According to the clinical data and 2015 American Thyroid Association (ATA) guidelines, patients were classified into 3 RET mutation risk groups: Modest, 24 cases; High, 48 cases; and Highest, 1 case. Multivariate analysis showed an increased likelihood of MTC stage III or IV at diagnosis with increasing of age and risk. The likelihood increased 11.6% per year of age at surgery (95% confidence interval, 1.040-1.198; P=0.002). The likelihood in patients with high risk was 7.9 times higher than patients with modest risk (95% confidence interval, 1.607-38.717; P=0.003). Aside from one patient with MEN2B, other 72 patients were MEN2A, of them, 28 cases from 7 kindreds with classical MEN2A (codon 634 & 618), 14 cases from 3 kindreds with cutaneous lichen amyloidosis (codon 634), 4 cases from 1 kindred with Hirschsprung's disease (codon 620), and 26 cases from 10 kindreds with familial MTC.

The aggressiveness of HMTC and the presentation of other endocrine diseases are related to specific RET mutations. For RET mutation carriers, MTC and other endocrine diseases should be diagnosed and treated early based on the RET genotypes.