Journal of medical genetics, 50(5), 309-323. BMJ Publishing Group Journal of Medical Genetics; Vol 50 Journal of Medical Genetics Journal of Medical Genetics, 50, 309-223 JOURNAL OF MEDICAL GENETICS, 50(5), 309-323. BMJ PUBLISHING GROUP Journal of Medical Genetics, vol. 50, no. 5, pp. 309-323 Journal of Medical Genetics, 50, 5, pp. 309-223