P336
Relationship between polymorphism of NOS3 gene and primary cardiac conduction disorders

 Inherited cardiac conduction diseases (CCD) are rare but are caused by mutations in a myriad of genes. Nitric oxide (NO) derived from endothelial NO synthase (NOS3) is crucial to ССD. Nitric oxide is a reactive free radical which acts as a biologic mediator in several processes, including neurotransmission and cardiac activities. Nitric oxide is synthesized from L-arginine by nitric oxide synthases. Multiple transcript variants encoding different isoforms have been found for this gene. 

Material and methods: 

A family examination was performed for 69 patients with atrioventricular block (AVB). The control group was formed by 220 patients without clinical ECG manifestations of cardiac diseases. All the examinees underwent ECG, echocardioscopy, electrophysiological examination of the heart.

 by results of research, it has been established that the frequency of carriers of a homozygous genotype on rare allele (4b/4b) among patients with AVB (26.1%±5.3) was higher in comparison with the controls (3.2%±1.2). The obvious tendency to decrease in carriers of a homozygous genotype on extended allele (4a/4a) among patients with AVB (47.8%±6.0) in comparison with the control group (71.4%±3.0) has also been noted. 

 In this work we revealed association between hereditary disturbances of cardiac conduction, such as AVB and polymorphism of NOS3 gene, using clinical - genetic material for the first time.