[1] Univ Newcastle Upon Tyne, Dept Biol, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England
[2] Univ Newcastle Upon Tyne, Dept Nutr Sci, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England
[3] Univ Newcastle Upon Tyne, Dept Human Genet, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England
[4] Wansbeck Dist Gen Hosp Trust, Ashington, England