Monday, June 15, 1998 Published at 23:28 GMT 00:28 UK
Celtic gene link to multiple sclerosis
Scottlsh Highlands: high rates of MS
Being Scottish could increase your risk of contracting multiple sclerosis, according to new study.
Researchers found that people with a surname beginning Mac or Mc were 24% more likely to have the disease than those without a Scottish name.
The incidence of MS increased with latitude, and the Orkney and Shetland islands had the highest rates in the world - double that in England and other parts of northern Europe.
Until now it had been assumed this was due to unidentified environmental factors specific to small island communities.
Doctors from the Department of Clinical Neurology, Radcliffe Infirmary, Oxford, identified all patients with a definite or probable diagnosis of MS between 1992 and 1995 living in the Lothian and Border regions of south-east Scotland.
The rate of new cases emerging during the study period reached 12.2 per 100,000 of population - the highest ever recorded.
The prefix Mac or Mc, meaning "son of" came into use in Scotland in the 13th century and could be used as a crude indicator of Celtic Scottish ancestry, said the researchers, led by Dr Peter Rothwell.
Of 1,613 MS patients living in the Lothian and Border regions on March 15,1995, a total of 589 had Scottish surnames beginning with one of the prefixes. The figure was significantly higher than the 476 expected based on the general frequency of Scottish names in the regions.
The findings indicated that Scotland as a whole had rates of MS as high as those found in Orkney and Shetland.
Prevalence of MS changed little as one travelled north in England and Wales, but rose sharply at the border with Scotland. This was difficult to explain in terms of environmental factors and suggested a genetic difference.
A study of telephone directories showed that the proportion of names beginning Mac or Mc shot up from 1-2% in England and Wales to 13.2% in the south of Scotland and 22.6% in the Highlands and islands.
This pointed to the English and Scots still having substantially different blood lines, despite considerable population mixing over the centuries.
The findings published in the Journal of Neurology, Neurosurgery and Psychiatry, were said to be evidence of a genetic predisposition to MS among the Scots.
They were also thought to explain the high prevalence of the disease in countries to which large numbers of Scots had emigrated, such as New Zealand.
The researchers concluded: "The very high prevalences of multiple sclerosis found in Orkney and Shetland are unlikely therefore to be due to peculiarities of the small island environments, and are more likely to be due to a genetic predisposition to the disease.
"Scottish ancestry appears to be a `risk factor' for the development of multiple sclerosis, and this may explain the high prevalence of the disease in countries in which there are significant numbers of Scottish migrants."