1. School of Clinical and Experimental Medicine, College of Medicine and Dentistry; University of Birmingham; Edgbaston; Birmingham; UK
2. West Midlands Regional Genetics Laboratories and Department of Clinical Genetics; Birmingham Women's Foundation Trust; Edgbaston; Birmingham; UK
3. South East Scotland Cytogenetics Service; Western General Hospital; Edinburgh; UK
4. Department of Obstetrics and Gynecology; Columbia University Medical Center; New York; NY; USA