Familial recurrence risks for multiple sclerosis in Australia
O'Gorman, C and Freeman, S and Taylor, BV and Butzkueven, H and Broadley, SA, Australian and New Zealand MS Genetics Consortium (ANZgene), Familial recurrence risks for multiple sclerosis in Australia, Journal of Neurology, Neurosurgery and Psychiatry, 82, (12) pp. 1351-1354. ISSN 0022-3050 (2011) [Refereed Article]
Background Genetic susceptibility to multiple sclerosis
(MS) has been recognised for many years. Considerable
data exist from the northern hemisphere regarding the
familial recurrence risks for MS, but there are few data
for the southern hemisphere and regions at lower
latitude such as Australia. To investigate the interaction
between environmental and genetic causative factors in
MS, the authors undertook a familial recurrence risk
study in three latitudinally distinct regions of Australia.
Methods Immediate and extended family pedigrees
have been collected for three cohorts of people with MS
in Queensland, Victoria and Tasmania spanning 158 of
latitude. Age of onset data from Queensland were
utilised to estimate age-adjusted recurrence rates.
Results Recurrence risks in Australia were significantly
lower than in studies from northern hemisphere
populations. The age-adjusted risk for siblings across
Australia was 2.13% compared with 3.5% for the
northern hemisphere. A similar pattern was seen for
other relatives. The risks to relatives were proportional to
the population risks for each site, and hence the sibling
recurrence-risk ratio (ls) was similar across all sites.
Discussion The familial recurrence risk of MS in
Australia is lower than in previously reported studies.
This is directly related to the lower population prevalence
of MS. The overall genetic susceptibility in Australia as
measured by the ls is similar to the northern
hemisphere, suggesting that the difference in population
risk is explained largely by environmental factors rather
than by genetic admixture.