RT Journal Article SR Electronic T1 Textbook of Human Genetics JF Journal of Medical Genetics JO J Med Genet FD BMJ Publishing Group Ltd SP 351 OP 351 DO 10.1136/jmg.26.5.351 VO 26 IS 5 A1 Read, Andrew P YR 1989 UL http://jmg.bmj.com/content/26/5/351.1.abstract AB