[1] Univ Birmingham, Queen Elizabeth Hosp, Div Med Sci, Birmingham B15 2TH, W Midlands, England
[2] Univ Birmingham, Queen Elizabeth Hosp, Div Reprod & Child Hlth, Birmingham B15 2TH, W Midlands, England
[3] Univ Newcastle Upon Tyne, Royal Victoria Infirm, Dept Pathol, Sch Clin & Lab Sci, Newcastle Upon Tyne NE1 4LP, Tyne & Wear, England