Genes and Multiple Sclerosis (MS): Understanding the Interconnection

What Role Do Genes Play in Multiple Sclerosis?

Genes are like tiny instruction books inside our bodies that tell our cells what to do. They also affect whether someone may develop a certain disease, such as multiple sclerosis (MS). MS is a disease that affects the brain and nerves, and scientists have found that genes play a significant role in its development. Research has shown that if someone in the family has MS, other family members might be more likely to get it too. Research has also shown that identical twins (who have the same genes) are more likely to get MS than twins who are not similar. Some special genes in the body help control the immune system, fight inflammation, and fix the protective covering of nerves called myelin. Changes in these genes can make it easier for MS to happen.

The human leukocyte antigen (HLA) genes, particularly the HLA-DRB1 gene located on chromosome 6, are among them. These genes help our immune system and sometimes can make the immune system a little too active. This can cause it to accidentally attack the body’s own nerves, which is a common occurrence in multiple sclerosis. These genes help explain why MS is an autoimmune disease. By learning more about the genes that cause MS, doctors can better understand the disease and develop personalized treatments that suit each person’s body.

Is Multiple Sclerosis Hereditary or Genetic?

No, multiple sclerosis cannot be directly inherited from the parents. But one might question: Does MS run in families? Yes, it can run, and if any sibling or parent is suffering from signs of MS, it can increase the risk of developing MS.

According to studies, if a sibling has MS, then the risk is one in 37. MS is not caused by a single gene but by a combination of factors. According to studies, multiple sclerosis has a heritability of around 50 percent. The remaining 50 percent depends on the environmental factors. However, not only genes play a role in the development of MS, but also environmental factors are involved in it.

Who Is More Likely to Get Multiple Sclerosis?

Anyone can get multiple sclerosis, but it happens more often in white people and women.

Here are some things that can make it more likely to get MS:

• If someone in your family, like a brother, sister, or parent, has MS.

• Certain genes are also seen in people with other immune system problems.

• Individuals affected by the Epstein-Barr virus during adolescence.

• Smoking makes it more likely to get MS.

Apart from this, individuals who spend more time in the sun or have high vitamin D levels are less likely to get MS.

What Is the Risk for Relatives of People With Multiple Sclerosis?

The risk of developing MS for relatives of people with MS usually depends on the type of relative.

• The risk in first-degree relatives is more than five times that in the general population. Or it can be 1 in 200.

• The risk in second- and third-degree relatives is 1 in 100.

• In the case of identical twins, the risk is 1 in 6.

• In the case of non-identical twins, the risk is 1 in 22.

Overall, the genetic contribution to MS is considered to be 50 percent.

Which Genes Can Increase the Risk of Developing MS?

Some genes can make it more likely for someone to get MS. These are

• HLA-DRB1 gene: This is one of the most important MS genes. Additionally, the presence of the HLA-DRB115:01 allele on the HLA-DRB1 gene increases the risk by three times. This HLA-DRB104:05 allele is considered a primary risk variant among the Japanese population.

• Others: Other genes linked to MS include IL7R (interleukin 7 receptor), IL2RA (interleukin 2 receptor alpha), CST7 (cystatin 7), and TNF (tumor necrosis factor).

Is Genetic Testing Available for Multiple Sclerosis?

No, there are no genetic tests available because many genes are involved in the development of MS, not one or two, along with environmental factors. If genes are involved in the development of MS, each gene exerts a small effect and contributes collectively to the overall risk.

There are tests for MS diagnosis, though none can predict it with certainty. However, few genetic tests have been discussed below, though this remains an area of active development.

What Advanced Genomic Technologies Hold Promise for Advancing MS Research?

A few advanced genomic technologies include:

• Single-cell sequencing: This technology enables the analysis of molecular and genetic profiles of individual cells. This technique can shed light on the diversity of immune cell populations seen in the central nervous system and how various cell types contribute to the pathophysiology of MS, helping researchers find new ways to treat MS.

• Epigenomic profiling: This analyzes the genome alterations that affect gene expression without changing the DNA (deoxyribonucleic acid) sequence.

• Next-generation sequencing (NGS): By enabling high-throughput sequencing of DNA and RNA (ribonucleic acid), NGS technologies would allow researchers to define multiple sclerosis's transcriptome and genomic landscapes thoroughly. Rare genetic variations, gene expression patterns, and alternative splicing events linked to MS susceptibility and development can be found using whole-genome, exome, and RNA sequencing techniques.

• CRISPR-Cas9 (clustered regularly interspaced short palindromic repeats and CRISPR-associated protein 9) genome editing: This technique allows for precise genome alteration and presents previously unheard-of possibilities for functional genomics research in multiple sclerosis. Scientists may examine the functional implications of genetic variations linked to MS susceptibility and disease development by introducing targeted genetic changes in animal models or cell lines.

What Are the Key Genetic Factors Implicated in MS Susceptibility?

Genetic factors that are involved in MS susceptibility include:

• Human leukocyte antigen (HLA) genes: A significant amount of research has been conducted on the relationship between MS susceptibility and HLA genes, particularly the HLA-DRB1 (human leukocyte antigen, class II, DR beta 1) gene located on chromosome 6. Substantial evidence links variations in HLA genes to a higher risk of MS development. These genes play a crucial role in the autoimmune response that underlies multiple sclerosis, as they regulate the immune system and help distinguish between self and non-self antigens.

• Cytokine genes: Multiple sclerosis susceptibility has also been linked to genes encoding other cytokines, including interleukins and tumor necrosis factors. These cytokines are essential for controlling inflammation and the immune system, both of which are dysregulated in multiple sclerosis. Genetic differences can influence the synthesis and function of these immune-signaling molecules in cytokine genes, which can affect sensitivity to

• Genes encoding chemokine receptors: Chemokines and their receptors have a role in immune cell trafficking and recruitment to inflammatory areas. Chemokine receptor gene variations influence immune cell migration and activation in the central nervous system and have been associated with an increased risk of MS. These genetic differences may impact the inflammatory response and have a role in the development of multiple sclerosis.

• Related genes to myelin: The development, maintenance, and repair of myelin have been linked to genes associated with MS vulnerability. Changes in these genes may affect the structure and function of myelin, thereby increasing the susceptibility of MS nerve fibers to immune-mediated injury.

• Immune regulatory genes: MS susceptibility has also been linked to genes involved in immune regulation and tolerance processes. A key aspect of the pathophysiology of multiple sclerosis is the dysregulation of immunological tolerance, which results in the breakdown of self-tolerance and the start of autoimmune reactions. Immune regulatory gene variations can disrupt these functions, potentially leading to MS development.

Further studies have shown that when mutations occur in genes associated with MS, gene mutations (changes in the DNA) can also increase the risk of developing MS.

Conclusion:

Multiple sclerosis, a complex nerve disorder, is strongly linked to genes, including its progression, severity, and even response to treatment. However, this condition is not hereditary; instead, the presence of this condition in the family can increase the risk of developing MS, especially among first-degree relatives. Research is being continued to test genes for early diagnosis and treatment.

Key Takeaways From iCliniq:

• Scientists have found that genes can influence whether someone is at risk of developing multiple sclerosis. One special gene, called HLA-DRB1, is crucial because it can increase a person's likelihood of developing MS.

• But MS doesn’t happen because of just one gene. It occurs when multiple factors, such as genes and the environment, interact.

If someone in your family has MS and you want to lower your chance of getting it, you can talk to our iCliniq neurologist to learn how to prevent it.