Atrial fibrillation is the most common persistent arrhythmia in adults; however, it is quite rare in children. In patients without structural heart diseases or extracardiac causes, the genetic basis of the arrhythmia can be assumed. A clinical case of atrial fibrillation in a child, probably associated with the variant D1907H in the SCN10A gene, was described in this article. In spite of a very limited clinical and genetic information on the association of Nav 1.8 channel encoded by SCN10A with atrial arrhythmias, the presented case can further confirm the role of this gene in arrhythmogenesis in children.