Polymorphismof non-coding sites of human mitochondrial genome andprimary disorders of cardiac conduction

Aim. Analysis of associations between idiopathic disturbances of cardiac conduction (DCC) and polymorphism of mitochondrial genome.
Material and methods. A family examination was performed in 431 probands with various DCC and
1347 relatives of the first, second and third degree of kinship (the study group). All the examinees were
divided into four subgroups. These included 158 probands with atrioventricular block (A VB) of various
degree and their 518 relatives (subgroup 1); 50 probands with a complete right bundle-branch block
(BBB) and their 161 relatives (subgroup 2); 108 probands with a complete left BBB and left anterior
branch of the His bundle and their 152 relatives (subgroup 3); 115 probands with sick sinus syndrome
(SSS) and their 327 relatives (subgroup 4). The control group consisted of 104 probands without clinical ECG manifestations of cardiac diseases and their 321 relatives. All the examinees have undergone
ECG, atropin test, echocardioscopy, electrophysiological examination of the heart and mitochondrial
DNA (mDNA).
Results. Comparison of the incidence of mDNA D-loop restriction sites in the group of patients with
idiopathic DCC and controls has found higher frequency of the Hae III 16517 site in the group of the
patients (p = 0.0480). By location of the blocks (atrioventricular and intraventricular), the site occurred more frequently in patients with AVB (86.36%). The variant "+" by the site of Hae III 16517
mDNA was found to associate with disturbances of cardiac conduction, more closely in AVB.
Conclusion. Variability of mDNA may be an etiological factor of idiopathic DCC pathogenesis.

mitochondrial human genome, cardiac conduction system, sick sinus syndrome, atrioventricular block, bundle-branch block