The latest research into genes suspected of playing a role in individual susceptibility to the devastating auto-immune disease multiple sclerosis (MS) may also provide new clues to some of its most puzzling aspects in New Zealand.
A co-ordinator of the transtasman study, Professor Trevor Kilpatrick, Melbourne University's director of neuroscience, said early today that the two newly discovered gene locations on chromosome 12 and 20 might reveal the "potential involvement" of vitamin D in the risk of developing MS and related auto-immune diseases.
Other studies in Australia recently revealed vitamin D directly interacts with the single strongest gene known to increase the risk of developing MS.
Vitamin D is primarily made in the skin, while intake from food accounts for a small proportion. It is direct exposure to sunlight that converts vitamin D into its active form.
Oxford University research has suggested that a child's lack of vitamin D in the womb or in early childhood can affect the development of their immune system, and that some people with a specific genetic pattern may have increased risk of aberrant immune cells developing and triggering an auto-immune disease such as MS.
This work has attracted attention not only because it suggests vitamin D supplement may have protective value, but it could also help to explain why the incidence of MS in New Zealand increases from the north of the country to the south, where sunlight levels are lower.
A New Zealand prevalence study released last year - the first in the world for a whole country - showed 2896 patients have been clinically diagnosed with MS, with a further 1220 potentially with the condition.
MS affects women at a rate three times that of men and is most often diagnosed in the late teens to early 30s. There is no cure.
It is most common in people with a European background, but there are a known 61 Maori with the disease, a rate of 17.5 per 100,000.
The prevalence increases from 50.8 people per 100,000 in Northland to 134.6 people per 100,000 in Southland, with a national average of 71.9. Confirmed cases include 720 men (including 19 Maori and one Pacific Islander), or 24.8 per 100,000, and 2176 women, including 42 Maori and one Pacific Islander), or 75.14 per hundred.