RT Journal Article SR Electronic T1 Supernumerary small ring chromosome. JF Journal of Medical Genetics JO J Med Genet FD BMJ Publishing Group Ltd SP 488 OP 488 DO 10.1136/jmg.15.6.488 VO 15 IS 6 A1 M S Lungarotti A1 A Calabro YR 1978 UL http://jmg.bmj.com/content/15/6/488.abstract AB