IKBKAP rs113994098: Understanding Familial Dysautonomia Carrier Status

What each genotype means

What is the rs113994098 Variant?

The variant rs113994098, often referred to in scientific literature as c.2204+6T>C or IVS20(+6T>C), is a single nucleotide change located within the IKBKAP gene. This gene is also frequently referred to as ELP1. The variant is classified as a splice-site mutation, meaning it alters the instructions the cell uses to correctly assemble the messenger RNA (mRNA) transcript of the gene. By disrupting the normal splicing process, this mutation leads to the production of an incorrect or reduced amount of the functional ELP1 protein. Because this variant is inherited in an autosomal recessive pattern, an individual must typically carry two copies of the mutation—one from each parent—to manifest the clinical symptoms of familial dysautonomia. It is considered a founder mutation, meaning it originated in a common ancestor and has been passed down through specific populations over many generations.

The Role of the IKBKAP/ELP1 Gene

The IKBKAP gene provides the genetic blueprint for the ELP1 protein, which is a critical component of the Elongator complex. This protein is found in various cells throughout the body, including those in the nervous system. ELP1 acts as a scaffold protein, helping to regulate kinases involved in essential cellular signaling pathways. In the context of familial dysautonomia, the reduction of functional ELP1 protein is particularly detrimental to the development and survival of sensory and autonomic neurons. When the gene is mutated, the resulting protein deficiency disrupts normal neuronal function, leading to the characteristic symptoms of the condition, such as impaired pain and temperature sensation, blood pressure instability, and difficulties with digestion and breathing. Research continues to explore how these molecular defects translate into the complex clinical presentation of the disease.

Research and Clinical Significance

The association between rs113994098 and familial dysautonomia is well-documented in clinical genetics. Studies have shown that this specific splice-site mutation is responsible for more than 99.5% of cases of familial dysautonomia in individuals of Ashkenazi Jewish descent. Because of this strong link, the variant is a primary target for carrier screening programs within this community. While the evidence for its role in causing the condition is robust, the clinical expression of the disease can vary, and the mutation is known to behave inconsistently across different cell types. It is important to note that being a carrier of a single copy of this variant does not typically result in the symptoms of familial dysautonomia. The evidence for this variant is focused on its role in carrier status and diagnostic testing rather than general population health risks.

Population Frequency

The rs113994098 variant is most prevalent in individuals of Ashkenazi Jewish ancestry. Population studies, including those using data from gnomAD, estimate the carrier frequency in this specific group to be approximately 1 in 30 to 1 in 32. This frequency is significantly higher than in the general global population, where the variant is considered extremely rare. The high prevalence within the Ashkenazi Jewish community is a hallmark of a founder effect, where the mutation became concentrated within a smaller, historically isolated population. Because of this distribution, genetic counseling and carrier screening are often recommended for individuals of Ashkenazi Jewish descent who are planning a family, as it allows them to understand their risk of passing the condition to their children.

What You Can Do With This Information

If you have received information regarding your status for the rs113994098 variant, it is important to view it in the context of your personal and family health history. This information is primarily used for reproductive planning and carrier screening. If you are a carrier, it does not mean you have the disease, but it does mean there is a possibility of passing the variant to your children. If both parents are carriers, there is a 25% chance for each pregnancy that the child will inherit two copies of the mutation and potentially develop familial dysautonomia. You cannot use this information to diagnose yourself or others. If you have concerns about your carrier status or family risk, the most appropriate step is to consult with a certified genetic counselor or a medical professional who can provide personalized guidance and discuss appropriate testing options.

Frequently asked questions

Sources & further reading

Related variants in IKBKAP