Autosomal dominant dilated cardiomyopathy with atrioventricular block: a lamin A/C defect-related disease.
OBJECTIVE
We investigated the prevalence of lamin A/C (LMNA) gene defects in familial and sporadic dilated cardiomyopathies (DCM) associated with atrioventricular block (AVB) or increased serum creatine-phosphokinase (sCPK), and the corresponding changes in myocardial and protein expression.


BACKGROUND
It has been reported that familial DCM, associated with conduction disturbances or variable myopathies, is causally linked to LMNA gene defects.


METHODS
The LMNA gene and myocardial ultrastructural and immunochemical changes were analyzed in 73 cases of DCM (49 pure, 15 with AVB [seven familial, eight sporadic], 9 with increased sCPK), four cases of familial AVB and 19 non-DCM heart diseases. The normal controls included eight heart donor biopsies for tissue studies and 107 subjects for LMNA gene studies.


RESULTS
Five novel LMNA mutations (K97E, E111X, R190W, E317K, four base pair insertion at 1,713 cDNA) were identified in five cases of familial autosomal dominant DCM with AVB (5/15: 33%). The LMNA expression of the myocyte nuclei was reduced or absent. Western blot protein analyses of three hearts with different mutations showed an additional 30-kDa band, suggesting a degrading effect of mutated on wild-type protein. Focal disruptions, bleb formation and nuclear pore clustering were documented by electron microscopy of the myocyte nuclear membranes. None of these changes and no mutations were found in the nine patients with DCM and increased sCPK or in the disease and normal controls.


CONCLUSIONS
The LMNA gene mutations account for 33% of the DCMs with AVB, all familial autosomal dominant. Increased sCPK in patients with DCM without AVB is not a useful predictor of LMNA mutation.
Arbustini
Eloisa
E
Molecular Diagnostic Division, IRCCS Policlinico San Matteo, Pavia, Italy. e.arbustini@smatteo.pv.it
Pilotto
Andrea
A
Repetto
Alessandra
A
Grasso
Maurizia
M
Negri
Andrea
A
Diegoli
Marta
M
Campana
Carlo
C
Scelsi
Laura
L
Baldini
Elisa
E
Gavazzi
Antonello
A
Tavazzi
Luigi
L
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D002311:Cardiomyopathy, Dilated / Q000097:blood / Q000150:complications* / Q000235:genetics*; D002648:Child; D002669:Child Welfare; D002675:Child, Preschool; D003402:Creatine Kinase / Q000097:blood / Q000235:genetics; D005192:Family Health; D005260:Female; D005500:Follow-Up Studies; D005799:Genes, Dominant / Q000235:genetics*; D006327:Heart Block / Q000097:blood / Q000150:complications* / Q000235:genetics*; D006801:Humans; D034904:Lamin Type A; D034882:Lamins; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics; D009206:Myocardium / Q000166:cytology / Q000473:pathology; D009687:Nuclear Proteins / Q000235:genetics*; D010375:Pedigree; D010641:Phenotype; D011110:Polymorphism, Genetic / Q000235:genetics; D011237:Predictive Value of Tests; D015995:Prevalence
D034904:Lamin Type A; D034882:Lamins; D009687:Nuclear Proteins; D003402:Creatine Kinase