A novel homozygous frameshift variant in MYO6 (c.2496_2497delAC; p.H833Qfs*5) was identified in a 2-month-old infant with congenital deafness and supraventricular tachycardia, raising the possibility that MYO6 dysfunction may contribute to arrhythmogenic susceptibility in addition to its established role in auditory function.
Key Findings
Results
A novel homozygous frameshift variant in MYO6 was identified in an infant with congenital deafness and supraventricular tachycardia.
The variant was c.2496_2497delAC; p.H833Qfs*5, a frameshift mutation in the MYO6 gene.
The variant was identified as homozygous.
Identification was performed via whole-exome sequencing followed by Sanger validation.
MYO6 variants were previously known causes of hereditary deafness and had been occasionally linked to hypertrophic cardiomyopathy and prolonged QT interval, but not SVT.
Results
The infant presented with recurrent paroxysmal supraventricular tachycardia (SVT) that was responsive to adenosine.
The patient was a 2-month-old male infant.
The infant experienced repeated SVT episodes.
SVT episodes were responsive to adenosine treatment.
Clinical evaluation included ECG, Holter monitoring, echocardiography, and laboratory studies.
Results
The infant had a markedly prolonged QTc interval of 569 ms measured during sinus rhythm.
QTc interval was 569 ms in sinus rhythm.
QT prolongation was noted as a cardiac finding in addition to the SVT.
MYO6 variants have occasionally been previously linked to prolonged QT interval in other reports.
Results
Echocardiography demonstrated mild left ventricular enlargement with preserved function and no structural anomalies.
Echocardiography showed mild LV enlargement.
Cardiac function was preserved despite the LV enlargement.
No structural anomalies were identified on echocardiography.
This distinguishes the cardiac phenotype from hypertrophic cardiomyopathy previously associated with MYO6 variants.
Results
The infant had bilateral congenital sensorineural hearing loss consistent with the established role of MYO6 in auditory function.
Hearing loss was bilateral and congenital in onset.
The hearing loss was sensorineural in type.
MYO6 variants are described as well-known causes of hereditary deafness.
Discussion
Supraventricular tachycardia had not previously been associated with MYO6 variants prior to this case report.
Prior cardiac associations with MYO6 included hypertrophic cardiomyopathy and prolonged QT interval.
The authors note that causality cannot be confirmed from this single observation.
The authors conclude that further studies are warranted to clarify the relationship between MYO6 variants and cardiac conduction abnormalities.
What This Means
This research describes a single case of a 2-month-old baby boy who had both congenital deafness and a serious heart rhythm problem called supraventricular tachycardia (SVT), where the heart beats abnormally fast. Genetic testing revealed that the infant carried two copies of a previously unreported mutation in a gene called MYO6, which is known to cause inherited deafness. The baby's heart also showed a dangerously prolonged electrical signal (QTc of 569 ms) and mild enlargement of the left chamber, though the heart was otherwise functioning normally. His SVT episodes were successfully treated with a medication called adenosine.
MYO6 mutations have previously been linked to deafness and, in some cases, to a type of thickened heart muscle disease and abnormal heart electrical timing. However, this is the first reported case linking a MYO6 mutation to SVT. This suggests that MYO6 may play a broader role in heart electrical activity than previously recognized, possibly making individuals with certain MYO6 mutations more susceptible to arrhythmias (irregular heartbeats).
The authors are careful to note that a single case report cannot prove that the MYO6 mutation caused the heart rhythm problems—it is possible the two conditions occurred together by chance. Nevertheless, this research suggests that clinicians evaluating patients with MYO6-related deafness may want to consider cardiac monitoring, and that scientists should investigate whether MYO6 has a functional role in heart electrical conduction. Larger studies examining cardiac outcomes in people with MYO6 mutations are needed to determine if a true link exists.
Kalayinia S, Masoumi T, Taherkhani A, Mahdieh N, Khorgami M, Maleki M. (2026). MYO6 and Heart: A Novel Variant in a Deaf Infant With Supraventricular Tachycardia.. Molecular genetics & genomic medicine. https://doi.org/10.1002/mgg3.70244