RET rs121913524: Understanding the C634R Variant
The rs121913524 variant in the RET gene, commonly known as C634R, is a rare genetic change linked to Multiple Endocrine Neoplasia Type 2A (MEN2A). This condition involves the development of tumors in hormone-producing glands, including the thyroid.
What each genotype means
Typical RET gene profile
This genotype represents the common, non-pathogenic sequence at this specific location in the RET gene. It is not associated with the increased risk of Multiple Endocrine Neoplasia Type 2A (MEN2A) or familial medullary thyroid carcinoma linked to this variant. Most individuals in the general population carry this genotype.
This is the most common genotype found in the general population.
Increased MEN2A risk
This genotype indicates the presence of a pathogenic missense variant (C634R) in the RET gene. This variant is associated with an increased risk of developing Multiple Endocrine Neoplasia Type 2A (MEN2A) and familial medullary thyroid carcinoma. Please consult with a clinical geneticist or your healthcare provider to discuss the implications of this finding for your health and family screening.
This genotype is extremely rare, with an allele frequency of less than 0.0001 in general population databases.
High risk variant profile
This genotype indicates that both copies of the RET gene carry the pathogenic C634R variant. While MEN2A is typically inherited in an autosomal dominant manner, individuals with this genotype are at a significantly elevated risk for the associated endocrine conditions. Clinical evaluation and genetic counseling are strongly recommended to understand the specific health implications.
This genotype is exceptionally rare and is not typically observed in general population cohorts.
What is the rs121913524 Variant?
The variant rs121913524, often referred to in clinical literature as C634R, is a specific change in the DNA sequence of the RET gene. In this context, the variant results in the substitution of the amino acid arginine for cysteine at position 634 of the RET protein. This specific alteration is classified as a missense mutation, meaning it changes the genetic code to produce a different protein building block than the one typically found at that location. Because the RET protein plays a critical role in cell signaling and development, changes to its structure can have significant biological consequences. This variant is primarily studied in the context of hereditary cancer predisposition syndromes, where it is identified through molecular genetic testing in individuals with a family history of endocrine tumors.
The Role of the RET Gene
The RET gene provides instructions for making a protein that is essential for the normal development of several types of nerve cells and the kidneys. This protein acts as a receptor, which means it sits on the surface of cells and receives chemical signals from the environment to trigger specific cellular activities. When the RET protein is activated, it initiates signaling pathways that control cell growth, differentiation, and survival. In the context of endocrine glands, proper RET signaling is vital for maintaining normal function. When mutations occur in this gene, they can lead to the protein being constantly turned on or malfunctioning, which may cause cells to grow and divide uncontrollably. This uncontrolled growth is a hallmark of the tumor development seen in conditions like Multiple Endocrine Neoplasia Type 2A.
Research and Clinical Associations
Scientific research has established a strong association between the C634R (rs121913524) variant and Multiple Endocrine Neoplasia Type 2A (MEN2A). MEN2A is a hereditary syndrome characterized by the development of medullary thyroid carcinoma, pheochromocytoma, and hyperparathyroidism. Clinical studies indicate that this specific variant is a well-documented cause of the syndrome, leading to a significantly elevated risk of developing these tumors compared to the general population. While the risk is high, the age at which these tumors appear can vary between individuals and families. It is important to note that the presence of this variant is a clinical finding that requires professional medical evaluation. Genetic counseling is typically recommended for individuals who test positive for this variant to discuss the implications for their health and the potential for screening family members.
What You Can Do With This Information
If you have received information about this variant, it is essential to understand that this is a clinical finding that should be discussed with a healthcare provider, such as a genetic counselor or an endocrinologist. This information is not a diagnosis in itself, but rather a piece of data that helps clinicians assess the risk of specific health conditions. You cannot use this information to self-diagnose or determine your own medical treatment. If you are concerned about your genetic risk, consult with a medical professional who can interpret these results in the context of your personal and family medical history. They can provide guidance on appropriate surveillance, such as regular blood tests or imaging, which may be recommended for individuals with this genetic predisposition to help detect potential issues early.
How common is this variant?
The rs121913524 variant is extremely rare, with a frequency of less than 0.0001 in general population databases like gnomAD.
Frequently asked questions
Is rs121913524 the same as C634R?
Yes, rs121913524 is the reference SNP ID (rsID) used in databases to identify the specific genetic location, while C634R is the protein-level description of the mutation (cysteine to arginine at position 634).
Does having this variant mean I have cancer?
No, having this variant does not mean you have cancer. It indicates an increased genetic predisposition to developing certain endocrine tumors, which is why medical surveillance is often recommended.
How is this variant tested?
This variant is typically identified through clinical molecular genetic testing, such as sequencing of the RET gene, often ordered by a doctor or genetic counselor after a clinical assessment.
Can I change my risk if I have this variant?
You cannot change your genetic sequence, but you can manage your health risks. Regular medical screening and consultation with specialists can help in the early detection and management of conditions associated with this variant.
Sources & further reading
Educational information only, last refreshed 9/20/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Synonymous polymorphism in the RET proto-oncogene exon 11 analyzed in medullary thyroid carcinoma and Hirschsprung disease risk models.
Associated with inherited susceptibility to multiple endocrine neoplasia type 2A and familial medullary thyroid carcinoma.
Missense mutation p.Cys634Arg in RET associated with Multiple Endocrine Neoplasia Type 2A (MEN2A).
A pathogenic missense variant (p.Cys634Arg) in the RET proto-oncogene associated with Multiple Endocrine Neoplasia type 2A (MEN2A).
A variant located in the RET gene, which is involved in various developmental processes including those relevant to ocular health.