Cys611Ser mutation in RET proto-oncogene in a kindred with medullary thyroid carcinoma and Hirschsprung's disease

Area of Science:

• Genetics and Molecular Biology
• Oncology
• Developmental Biology

Background:

• Germline mutations in the RET proto-oncogene are linked to hereditary conditions like Multiple Endocrine Neoplasia (MEN) types 2A and 2B, familial medullary thyroid carcinoma (FMTC), and Hirschsprung's disease (HSCR).
• Previous studies indicated that RET gene mutations at cysteine residues 609, 618, or 620 are associated with families exhibiting both MEN 2A/FMTC and HSCR.
• Understanding the specific RET mutations is crucial for diagnosing and potentially treating these complex hereditary disorders.

Observation:

• A novel germline mutation in the RET gene at cysteine 611 was identified in a Japanese family.
• This mutation resulted in an amino acid substitution from cysteine to serine at codon 611.
• The family presented with a dual diagnosis of medullary thyroid carcinoma and Hirschsprung's disease.

Findings:

• The identified RET gene mutation at cysteine 611 provides a new genetic link between medullary thyroid carcinoma and Hirschsprung's disease.
• Biological and biochemical analyses support the hypothesis that substitutions at cysteine 611, similar to those at 609, 618, and 620, can promote the development of both MEN 2A/FMTC and HSCR.
• This clinical case validates previous predictions regarding the pathogenic mechanism of RET mutations in these co-occurring diseases.

Implications:

• The findings suggest that RET mutations affecting cysteine residues, including the newly identified C611S, are critical in the pathogenesis of both MEN 2A/FMTC and HSCR.
• This discovery may lead to improved genetic screening and diagnostic approaches for families at risk of these related hereditary conditions.
• Further research into the functional consequences of RET cysteine mutations could reveal novel therapeutic targets.