RT Journal Article SR Electronic T1 'Mirror image' chromosome No. 21. JF Journal of Medical Genetics JO J Med Genet FD BMJ Publishing Group Ltd SP 152 OP 153 DO 10.1136/jmg.14.2.152 VO 14 IS 2 A1 J Harvey A1 S Wiener A1 R Birner YR 1977 UL http://jmg.bmj.com/content/14/2/152.abstract AB