New Genetic Variant Affects Inheritance of Multiple Sclerosis
Single nucleotide polymorphisms account for 30 percent of genome variance in those with MS.
--by Nina Lincoff
Multiple sclerosis (MS) is an inflammatory autoimmune disease that affects the brain and spine and is most common among young adults. It can be a devastating disease resulting in loss of cognitive and motor function. Currently, there are close to 400,000 people living with MS in the United States. Interest in different therapeutic approaches to treating MS has been a focus of medical research because of the disease’s proclivity for drastically altering the lives of young adults.
environmental factors affect susceptibility, those with first relatives
who have MS are at a greater risk for developing the disease. It has
long been known that some MS traits are hereditary. Contribution of
alleles—misbehaving genes—from the major histocompatibility complex
(MHC) is known to increase MS risk.
However, researchers from the United Kingdom were curious about the effects of lesser-observed loci. In a study published by Scientific Reports, researchers reveal that there are genomic variants outside of the MHC that affect MS risk. Single nucleotide polymorphisms (SNPs), which are located on chromosome 6, account for approximately 30 percent of genomic variance between MS patients and their healthy peers.
SNPs are the most common genetic variant, and each SNP corresponds to a single difference in a single nucleotide.
Genome-wide genotype data for more than 475,000 autosomal single nucleotide polymorphisms (SNPs) was collected from nearly 2,000 MS patients and more than 5,000 controls in the United Kingdom. Data was adjusted for relatedness and population structure. Researchers culled information from the genome-wide association studies and concluded that 30.7 percent of MS heritability is explained by variants including SNPs on chromosome 6. MHC, which includes some SNPs variance, increases MS risk by two.
The Expert Take
“It was surprising how little we actually know about MS genetics—70 percent of the genetic basis of MS remains unexplained,” said study author Sreeram Ramagopalan in an email to Healthline. Stopping at just one answer, like the relevance of MHC associations and SNPs, is not enough. The human genome is complex, and there is much more to be learned.
“Genes do play a role in determining the risk of MS, but we do not yet know all the genetic factors involved. Once we do, this will give us a better picture of the causes of the disease and should help treatment and prevention strategies,” said Ramagopalan.
Being able to identify MS variants in the human genome “would be very important for personalized care and possibly to predict treatment response to therapies, particularly biological products,” said June Halper, an MS nurse and advocate.
Halper said that further study in finding biomarkers to identify early MS, preventing cognitive impairment, and determining treatment response more definitively would be beneficial.
Part of the MS genomic puzzle has been pieced together, but it’s not nearly complete. While SNPs do show a 30 percent variance in liability to MS, there is still much to be explored in terms of hereditary MS risk. The ability to predict MS based on the human genome with accuracy would be indispensable for preventing and treating a debilitating disease. Even with this progress, as Ramagopalan said, 70 percent of the genetic aspects of MS still remain unknown.
The efficacy of MHC on MS risk was previously explored by Ramagopalan in 2009, and was found to greatly influence MS severity.