Study of the RET gene and his implication in thyroid cancer: Morocco case family.

BACKGROUND Multiple endocrine neoplasia type 2A (MEN 2A) is an autosomal dominant inherited cancer syndrome that affects multiple tissues derived from the neural crest. Inheritance of MTC is related to the presence of specific mutations in the RET proto-oncogene. Almost all mutations in MEN 2A involve one of the cysteines in the extracellular domain of the RET receptor. AIMS The objective of the present study was the biochemical and molecular characterization of the first Moroccan clinically established MEN 2A patient and at-risk family members. SETTINGS AND DESIGN This is a study on a family presented with MTC referred to our institute in 2004. MATERIALS AND METHODS Peripheral blood leukocyte DNA samples were isolated and amplified by polymerase chain reaction followed by restriction enzyme analysis and DNA sequencing. RESULTS We identified a heterozygous germ line missense mutation at codon 634 of exon 11 in the RET gene that causes a cysteine to arginine amino acid substitution in the DNA of the proband; this mutation was not found in the DNA of the parents or relatives. CONCLUSIONS The detection of mutated MEN 2A gene carriers enables us to differentiate high-risk members from those who bear the wild-type gene. Occasionally, application of RET proto-oncogene testing may lead to the detection of unexpected de novo mutation that could be transmitted to children.