Familial Skeletal Myopathy with Atrioventricular Block.

Abstract

Objective Westudied familial cases of skeletal myopathy with atrial fibrillation (Af) and atrioventricular (AV)block to comparethe clinical features to other myopathies associated with cardiac abnormalities. MethodsNeurologic, cardiologic, electrophysiologic, muscle pathology, and genetic studies were performed on the patients showing muscle weakness. Patients Four patients (a 63-year-old mother, 30 and 32-year-old sisters, and their maternal grandmother) and three healthy family membersfrom three generations were studied. The modeof inheritance was suspected as autosomal dominant. Results Twosisters with congenital myopathy without rigid spine developed Af and AVblock at the age of 28 and 18, respectively. The mother showed AV block, and underwent pacemaker implantation at the age of 63. The maternal grandmother had dilated cardiomyopathy, Af and severe lordosis. She died of stroke attacks and congestive heart failure at the age of 78. Muscle biopsy obtained from the mother and sisters showed myopathic changes without characteristic abnormalities. No mitochondrial DNAmutations were found. Other inherited myopathies with cardiac complications were not suspected in this family. ConclusionThis Japanese family appears to belong to a new genetically heterogeneous group of autosomal dominant skeletal myopathy with severe AVblock and Af. (Internal Medicine 38: 856-860, 1999)

Cardiac Muscle Involvement in Muscle Disorders

“…However,the nuclear membrane in muscle biopsies from patients is positively stained with anti-lamin A/C antibody. Although Ohkubo et al (1) excluded the possibility of autosomal dominant Emery -Dreifuss muscular dystrophy in the present familial patients, the clinical and pathologic findings in their family are not that different from the disease. Further genetic analysis on this family will provide additional knowledge for understanding the pathogenesis of AVblock in relation to Emery-Dreifuss muscular dystrophy.…”

Atrial fibrillation/flutter in myopathies

“…Stroke has been particularly reported in patients with BMD [18], X-linked EDMD [19], autosomal dominant EDMD [19,20], FSH [21], MD1 [3], FA [3]. or non-specific myopathy [22]. Evidence for cerebral infarction was present in only 2 of the 131 patients with various myopathies mentioned above (1.5%) [3].…”

Is Atrial Fibrillation a Genetic Disease?

“…AF has been described in other cardiac monogenic diseases as a concomitant disease. It has been identified in families with hypertrophic cardiomyopathy, 17 skeletal myopathies, 18 familial amyloidosis, 19 and in monogenic diseases predisposing to atrial abnormalities 20 . In these cases, the disease is probably related to morphological changes in the atria caused by the underlying cardiac pathology.…”