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A model for GFR alpha 4 function and a potential modifying role in multiple endocrine neoplasia 2
Judith B Vanhorne1, Scott D Andrew, Karen J Harrison
1Department of Pathology, Queen's University, Kingston, ON, Canada K7L 3N6.
Oncogene
|December 14, 2004
Summary
Genetic variants in GFRA4 may contribute to multiple endocrine neoplasia type 2 (MEN 2) when RET mutations are absent or modify disease presentation. GFRA4 alterations could impact RET signaling complexes, influencing MEN 2 development.
Area of Science:
- Endocrinology
- Human Genetics
- Oncology
Background:
- Multiple endocrine neoplasia type 2 (MEN 2) is an inherited cancer syndrome primarily linked to RET proto-oncogene mutations.
- A subset of MEN 2 cases lack detectable RET mutations, and significant phenotypic variability exists, suggesting involvement of other genetic factors.
- Glial cell line-derived neurotrophic factor receptor alpha 4 (GFRA4) is a candidate gene, encoding a co-receptor essential for RET signaling.
Purpose of the Study:
- To investigate the role of GFRA4 mutations in MEN 2 pathogenesis, particularly in patients without RET mutations.
- To explore whether GFRA4 variants contribute to the phenotypic diversity observed in MEN 2.
Main Methods:
- Screening of GFRA4 gene for variants in patients with MEN 2 or MEN 2-like phenotypes, with and without known RET mutations.
- Analysis of identified GFRA4 variants for potential impact on gene expression and protein isoform function.
Main Results:
- Ten GFRA4 variants were identified; three were found to be significantly associated with the patient cohorts.
- One variant, a single-base substitution upstream of the coding region, may affect GFRA4 gene expression.
- A 7 bp insertion variant was identified that alters the reading frame of all GFRA4 isoforms, potentially affecting RET signaling complex formation.
Conclusions:
- GFRA4 variants represent a potential contributing factor to MEN 2, especially in RET-negative cases.
- Alterations in GFRA4 isoforms and their interaction with RET may explain some phenotypic variations in MEN 2.
- A model for wild-type GFRA4 isoform expression involving both activating and inhibiting RET co-receptors is proposed.