Multiple Sclerosis Development Influenced by Environmental Factors

Individual genetic backdrop may be less important than previously thought in the development of multiple sclerosis.

Environmental factors may play a greater role in the development of multiple sclerosis (MS) than previously thought, according to researchers.

“MS is a disease where genetic ancestry and environmental factors play a role, however to what degree these two aspects are driving the risk of developing MS remains unknown,” said lead study author Klaus Schmierer.

A study published in Multiple Sclerosis Journal used electronic records from general practices (GPs) queried for the number of patients with MS and grouped by ethnicity, in 4 east London boroughs: City of London, Hackney, Newham, and Tower Hamlets.

The results of the study showed that in east London, 776 patients were diagnosed with MS out of the 907,151 individuals registered with GPs. The overall prevalence was 111 per 100,000 with 152 for women and 70 for men. The prevalence per 100,000 was 180 for whites, 74 for blacks, and 79 for South Asians.

MS was found to be significantly more prevalent among black people and South Asians who were living in London, versus individuals who live in their ancestral territory.

“We found that people of Asian and African extraction in London are far more likely to have MS than people of the same ethnicity living in their ancestral countries,” Schmierer said. “Our early results suggest that environmental factors play a pivotal role in the risk of developing MS, whilst the individual genetic backdrop may be of lesser importance.”

The differences in prevalence can be explained by less MS diagnosis in less resourced countries, but it doesn’t explain the gulf in prevalence between these territories. Additionally, increased exposure to environmental agents or behaviors in the UK that initiate the development of MS can also be an explanation, but further research needs to be conducted.

“If we can clearly define the cluster of risk factors, and their proportional relevance, measures could be developed to change or remove these factors -- thereby potentially eradicating MS, which is our ultimate goal,” Schmierer said.

The study had little risk for biases in ethnicity data, but individuals with MS that were missed in the GP datasets is a possibility, leading researchers to believe there is a likelihood that they underestimated the prevalence by about a quarter.