Relation of cardiac abnormalities and CTG-repeat size in myotonic dystrophy.
It is unclear if the severity of cardiac involvement in patients with myotonic dystrophy (MD) is related to the size of the CTG-repeat expansion. This open, uncontrolled, observational, prospective study aimed to find out if there is a relation between the severity of cardiac involvement in MD and the CTG-repeat size. In 21 patients with MD, (8 women, 13 men, aged 11-88 years) a detailed cardiologic examination, including history, clinical examination, electrocardiography (ECG), transthoracic echocardiography and ambulatory 24-h ECG, was carried out and cardiac involvement was assessed according to a previously described scoring system. Additionally, the CTG-repeat size was determined from nuclear DNA of blood leukocytes. The correlation between the CTG-repeat size and the mean heart rate, PQ-interval, QTc-interval, fractional shortening, left ventricular enddiastolic diameter, septal thickness, posterior wall thickness, mean heart rate on 24-h ECG and cardiac involvement score was r=0.47, r=0.086, r=0.11, r=-0.27, r=-0.34, r=-0.06, r=-0.12, r=0.16 and r=0.09 (all p>0.05), respectively. In patients 21-30, 31-40 and 41-50 years of age, cardiac involvement increased with increasing CTG-repeat size. In younger patients, the number of CTG-repeats needed to develop a reasonable cardiac involvement was higher than in older patients. Depending on age, cardiac involvement increases with increasing CTG-repeat size obtained from blood leukocytes in patients with MD.
Finsterer
J
J
Ludwig Boltzmann Institute for Research in Epilepsy and Neuromuscular Disorders, Austria.
Gharehbaghi-Schnell
E
E
Stöllberger
C
C
Fheodoroff
K
K
Seiser
A
A
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D004247:DNA / Q000235:genetics; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009223:Myotonic Dystrophy / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology; D019680:Trinucleotide Repeat Expansion; D018911:Trinucleotide Repeats / Q000235:genetics*
D004247:DNA