Malalignment of the sarcomeric filaments in hypertrophic cardiomyopathy with cardiac myosin heavy chain gene mutation.
OBJECTIVE
To investigate changes in the alignment of the sarcomeric filaments in hypertrophic cardiomyopathy and the effects of cardiac beta myosin heavy chain (beta-MHC) mutation on the sarcomeric ultrastructure.


METHODS
A retrospective analysis.


METHODS
Endomyocardial biopsy samples were examined by transmission electron microscopy in seven patients with hypertrophic cardiomyopathy and beta-MHC mutation, six with hypertrophic cardiomyopathy but without the mutation, and five controls (with chest pain syndromes).


METHODS
Alignment of the sarcomeric filaments and the distance between neighbouring thick myosin filaments.


RESULTS
In controls, cross sections of the sarcomere at the A band showed a highly organised orthohexagonal array with 6 thin actin filaments surrounding one thick myosin filament, whereas in hypertrophic cardiomyopathy the alignment of the sarcomeric filaments was sparse and disrupted. In hypertrophic cardiomyopathy with a mutation, the distance between neighbouring thick myosin filaments was greater than in controls (mean (SD) 45.3 (4.7) v 38.5 (3.5) nm, p < 0.05), and the variance of the distance was greater than in controls (8.0 (0.7) v 4.8 (1.0) nm, p < 0.001) or in patients with hypertrophic cardiomyopathy without a mutation (6.7 (0.6) nm, p < 0.05). In the latter, the variance of the distance was also greater than in the controls (p < 0.01). A significant correlation was found between the grade of the myocyte hypertrophy and the variance of the distance (r = 0.654; p < 0.01).


CONCLUSIONS
The alignment of the sarcomeric filaments is disrupted in hypertrophic cardiomyopathy, particularly when there is beta-MHC mutation.
Muraishi
A
A
The Third Department of Internal Medicine, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka 830-0011, Japan.
Kai
H
H
Adachi
K
K
Nishi
H
H
Imaizumi
T
T
D000293:Adolescent; D000328:Adult; D002312:Cardiomyopathy, Hypertrophic / Q000235:genetics* / Q000473:pathology*; D016022:Case-Control Studies; D004252:DNA Mutational Analysis; D005260:Female; D006801:Humans; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged; D009154:Mutation; D018995:Myosin Heavy Chains / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012518:Sarcomeres / Q000648:ultrastructure*
D018995:Myosin Heavy Chains