MYO6 and Heart: A Novel Variant in a Deaf Infant With Supraventricular Tachycardia

Variants in MYO6 are well known causes of hereditary deafness and have occasionally been linked to cardiac abnormalities, including hypertrophic cardiomyopathy and prolonged QT interval. However, supraventricular tachycardia (SVT) has not previously been associated with this gene.

To describe a neonate with congenital deafness, paroxysmal SVT, and QT prolongation carrying a novel homozygous MYO6 variant.

A 2-month-old male infant with bilateral congenital sensorineural hearing loss presented with recurrent paroxysmal SVT. Clinical evaluation included ECG, Holter monitoring, echocardiography, and laboratory studies. Whole-exome sequencing followed by Sanger validation was performed to identify genetic alterations.

The infant experienced repeated SVT episodes responsive to adenosine and was noted to have a prolonged QTc interval of 569 ms in sinus rhythm. Echocardiography showed mild LV enlargement with preserved function and no structural anomalies. Genetic testing revealed a novel homozygous frameshift variant in MYO6 (c.2496_2497delAC; p.H833Qfs*5).

While causality cannot be confirmed, this observation raises the possibility that MYO6 dysfunction may contribute to arrhythmogenic susceptibility in addition to its established role in auditory function. Further studies are warranted to clarify the relationship between MYO6 variants and cardiac conduction abnormalities.