Genetic disorders of pediatric MEN2A patients in the south of Spain

Abstract

Medullary thyroid carcinoma (MTC) is observed in nearly 100 % of patients with multiple endocrine neoplasia type 2A (MEN2A). The gene responsible for MEN2A is the RET proto-oncogene and about 95 % of MEN2A patients have germline mutations in five specific cysteine codons (609, 611, 618, 620 and 634). A retrospective study of children from families with MEN2A in our geographic area was performed. Variables analyzed included demographic data, kinship relations, age at genetic screening, age at prophylactic thyroidectomy, genetic mutation subtype and histological findings. The genetic study consisted in direct molecular analysis by automatic sequencing of RET mutated exon in the studied family. We performed 13 prophylactic total thyroidectomies from 1997 to 2013, 8 females and 5 males. The mean age at genetic diagnosis was 3.8 years (range 2-5.9). All children belonged to four interconnected families living in the same geographic area and presenting C634Y mutation in all the cases. The mean age at prophylactic thyroidectomy was 5.6 years (range 4-8.5). Histopathological findings demonstrated seven cases of C-cells nodular hyperplasia, one lymphocytic thyroiditis, two without evidence of disease, two micro-carcinomas and one multicentric carcinoma. The mutation found in the RET proto-oncogene responsible for MEN2A in pediatric patients in the south of Spain is the C635Y. It is considered a high-risk mutation, associated with an earlier malignant transformation and development of MTC.