RT Journal Article SR Electronic T1 ABH secretor status of the fetus: a genetic marker identifiable by amniocentesis. JF Journal of Medical Genetics JO J Med Genet FD BMJ Publishing Group Ltd SP 438 OP 440 DO 10.1136/jmg.8.4.438 VO 8 IS 4 A1 P Harper A1 W B Bias A1 J R Hutchinson A1 V A McKusick YR 1971 UL http://jmg.bmj.com/content/8/4/438.abstract AB