RR-PO-0984

Tuesday 12:30, Palau de Congressos, Exhibition Hall  [Display No. 534]

MOLECULAR AND CLINICAL STUDIES IN MYOTONIC DYSTROPHY -THE RELATION BETWEEN TRINUCLEOTIDE REPEAT AND MUSCLE STRENGTH-. Kozuka N1), Tachi N1), Kikuchi S2), Uchida E2), Horimoto Y2), Sengoku Y1), Takeda H1)  1) School of Health Sciences. Sapporo Medical University. Sapporo. Japan.  2) Graduate school of health sciences. Sapporo Medical University. Sapporo. Japan. PURPOSE: Myotonic dystrophy(DM) is a hereditary neuromuscular disorder of an autosomal dominant trait. DM is caused by an expansion of unstable CTG trinucleotide repeat(CTG repeat) in the 3' untranslated region of mRNA coding myotonin protein kinase(MT-PK). It is generally agreed that an approximate correlation has been demonstrated between the degree of CTG repeat expansion and clinical severity among DM patients. The purpose of this study was to discuss the relation between an expansion of a CTG repeat in DM and their muscle strength. RELEVANCE: For physical therapists, evaluating the change of clinical features in progressive disease is an important work. This study provides useful information for understanding the change of severity in DM. SUBJECTS: 4 families consisted of 8 patients (5 congenital DM and 3 adult onset or carrier DM) were studied. All patients were informed of DM and consented to be performed genetic analysis and muscle test. For the normal control, 2 advanced students groups (13 men and 14 women) were included. METHOD: To detect an expansion of CTG repeat, polymerase chain reaction(PCR) and non-radioactive Southern blot analysis were performed. For evaluation of muscle strength, grip power, back muscles' power, isometric extension and flexion strength of the knee, isometric dorsi and plantar flexion strength were measured. RESULTS: By the Southern blot analysis, DNA fragment including CTG repeat were detected. In normal control subjects, the number of CTG repeat were under 20 repeat. In contrast, in the congenital DM, the number of CTG repeat were expanded over 2000 repeat and in the adult onset or carrier DM, the number of CTG repeat were about 100-1500. Grip power, back muscles' power, plantar flexion strength tended to decrease in inverse relation to the size of CTG repeat, though, others were not related. CONCLUSIONS: These results demonstrated anticipation. We conclude that the genetic analysis provides useful information for evaluating muscular power of DM patients.