RT Journal Article SR Electronic T1 Comparison of CTG repeat length expansion and clinical progression of myotonic dystrophy over a five year period. JF Journal of Medical Genetics JO J Med Genet FD BMJ Publishing Group Ltd SP 593 OP 596 DO 10.1136/jmg.32.8.593 VO 32 IS 8 A1 L Martorell A1 J M Martinez A1 N Carey A1 K Johnson A1 M Baiget YR 1995 UL http://jmg.bmj.com/content/32/8/593.abstract AB Myotonic dystrophy (DM) is associated with an underlying CTG trinucleotide repeat expansion at a locus on chromosome 19q13.3. We have determined the repeat length in 23 DM patients with varying clinical severity of symptoms and various sizes of repeat amplification. We confirm that as in previous studies there is no strong correlation between repeat length and clinical symptoms but find that the repeat length in peripheral blood cells of patients increases over a time span of five years indicating continuing mitotic instability of the repeat throughout life. Repeat length progression does not appear to be indicative of clinical progression but age probably is. The degree of expansion correlates with the initial repeat size and 50% of the patients with continuing expansions showed clinical progression of their disease symptoms over the five year study period.