RT Journal Article SR Electronic T1 Presymptomatic detection and prenatal diagnosis for myotonic dystrophy by means of linked DNA markers. JF Journal of Medical Genetics JO J Med Genet FD BMJ Publishing Group Ltd SP 750 OP 754 DO 10.1136/jmg.26.12.750 VO 26 IS 12 A1 Norman, A M A1 Floyd, J L A1 Meredith, A L A1 Harper, P S YR 1989 UL http://jmg.bmj.com/content/26/12/750.abstract AB The close genetic linkage between the loci for apolipoprotein CII (ApoCII) and myotonic dystrophy makes presymptomatic detection and prenatal diagnosis feasible. We report three years' service experience of providing presymptomatic detection and prenatal diagnosis for myotonic dystrophy in 99 families. Careful clinical study of older family members remains important. The introduction of new probes (CKMM and BCL4) has helped to solve the problem of uninformativeness owing to unhelpful genotype distribution in a family. Nevertheless, informativeness cannot be guaranteed and families should be studied before pregnancy is undertaken whenever possible. Presymptomatic testing and prenatal diagnosis for myotonic dystrophy are soundly based. All affected subjects should have DNA banked for future use when other family members may require genotype information.