Saturday, 15 November 2014

Faroe Island genetic stock does not confer undue risk of MS

Binzer S, Imrell K, Binzer M, Kyvik KO, Hillert J, Stenager E. High inbreeding in the Faroe Islands does not appear to constitute a risk factor for multiple sclerosis. Mult Scler. 2014 Nov 12. pii: 1352458514557305. [Epub ahead of print]

BACKGROUND:Large population-based genome-wide association studies have identified several multiple sclerosis (MS) genetic risk variants, but the existing missing heritability warrants different strategies. Isolated populations offer an alternative way of searching for rare genetic variants and evaluating the possible role of consanguinity in the development of MS. Studies of consanguinity and MS risk have yielded conflicting results.
OBJECTIVES:In this study we investigated the role of consanguinity on MS risk in the relatively isolated Faroe Islands, which have a presumed high level of inbreeding.
METHODS:A total of 29 cases and 28 matched controls were genotyped and assessed for inbreeding coefficients, number of runs of homozygosity (ROH) at different lengths and observed number of homozygotes as measures of relatedness. Parametric and non-parametric statistical models were applied.
RESULTS:Both cases and controls exhibited considerable relatedness demonstrated by very high inbreeding coefficients, large number of observed homozygotes and many long ROH. However, apart from the number of ROH ≥ 2.5 mega base pairs, no significant differences between the two groups were observed.
CONCLUSIONS:Overall, no significant difference between cases and controls were found, indicating that consanguinity in itself does not appear to be an important risk factor for MS in the population of the Faroe Islands.

The small number of people on islands leads to a small gene pool and should this gene pool contain disease related genes then there could be a disproportionate number of people with disease. For example Bowen-Condrati Syndrome,  which is characterized by an extreme delay in growth, and most children born with this genetic disease don't live past six months. A fatal switch in the EMG1 gene happens in roughly one out of every 355 Hutterite (a group that lives in small communities in the USA..who have created an functional island by their mentality of non-integration into other communities within the US) births.   

With common ancestry you will have common genes. You get one set from your mum and one from your dad and in many people there will be different (Heterozygous) but with a limited gene pool the chances of them being the same is increased and mum and dads genes will be the same (Homozygous). In people from the Faroe islands they find evidence of common shared genes. Here they state that it does not appear to affect MS risk. However why would it?

MS appeared in the Faroe islands after World War two, suggesting that the British brought MS with them. However, the genes in the Faroe Islanders had been without MS for many years before WWII and so it is not surprising that the consanguinitiy (same blood or relative inbreeding) does not seem to be an issue in MS, as the cosanguinity would have been there long before MS and maybe the lack of co-sangunity as would be more relevant as it could introduce more (MS) genes into the gene pool. 

We that genes influence your risk of developing MS and we know the identity of about 160 genetic loci conferring susceptibility. If you had people with MS marrying and breeding (Conjugal MS) then the chances of having children with MS increases compared to the population level

3 comments:

  1. Surely today's big news is Lemtrada approved in US?

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    Replies
    1. Re: "Surely today's big news is Lemtrada approved in US?"

      Yes, it is. I only heard late yesterday en-route to Newark airport and didn't have time to post on it. I was late and nearly missed my flight. I could only get to it this morning. Overall it is good news.

      Delete
  2. Inbreeding? Are they talking about the sheep?:-) I can't believe people live up there. I guess it's better than Detroit:-)

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