[Molecular biology, basic research and diagnosis of Hirschsprung's disease].

The proto-oncogene RET is the major gene responsible for Hirschsprung's disease (HSCR), with RET mutations also implied in different pathologies. A variety of mutations of the RET proto-oncogene have been detected in HSCR patients. Special attention should be paid to rare patients who carry mutations of one of the critical cysteine residues of these exons, known to predispose to MEN2A. In these cases, HSCR can be associated with the development of neuroendocrine tumors such as medullary thyroid carcinoma (MTC) or MEN2A, for which a prophylactic thyroidectomy is advisable in the presence of a tumor causing RET mutation. In combined MEN2A/HSCR families, RET gene testing, tumor screening and prophylactic thyroidectomy are indicated as in MEN2A. The multigenic origin of HSCR and the absence of a "standard" RET mutation associated with HSCR currently make a routine molecular diagnosis impossible.