Ventricular arrhythmias and sudden death in Rhodesian Ridgebacks

Ventricular arrhythmias are heart rhythm disturbances that originate in the heart's ventricular musculature. They are manifested by a significant palpitation and a decrease in minute cardiac output, leading to shortness of breath, fatigue, hypotension, and even sudden cardiac death.

A missense mutation c.325G>A in the MICOS13 gene (formerly QIL1) has been identified in Rhodesian Ridgebacks that is strongly associated with ventricular arrhythmias. MICOS13 is part of the mitochondria and is important in cellular energy production. In its dysfunction, we observe hyperplastic mitochondria with abnormal disarranged cristae, lipid bodies and inclusions.

The mode of inheritance of the mutation is probably autosomal recessive. This means that only individuals who inherit the mutated gene from both parents will develop the disease. Carriers of the mutated gene are clinically healthy but pass the mutation on to their offspring. In the case of a mating between two heterozygous individuals, theoretically 25% of the offspring will be completely healthy, 50% of the offspring will be carriers and 25% of the offspring will inherit the mutated gene from both parents and will therefore be affected by the disease.

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Reference:

Meurs, K.M., Friedenberg, S.G., Olby, N.J., Condit, J., Weidman, J., Rosenthal, S., Shelton, G.D. : A QIL1 variant associated with ventricular arrhythmias and sudden cardiac death in the juvenile Rhodesian Ridgeback dog. Genes (Basel) 10:168, 2019. Pubmed reference: 30795627