RT Journal Article SR Electronic T1 Birth Defects: Original Article Series, V, 2 JF Journal of Medical Genetics JO J Med Genet FD BMJ Publishing Group Ltd SP 251 OP 252 DO 10.1136/jmg.8.2.251-a VO 8 IS 2 A1 J. Insley YR 1971 UL http://jmg.bmj.com/content/8/2/251.2.abstract AB