This case series was conducted to help better characterize the MTCYB gene variants identified in patients with atrial fibrillation. It involved 30 hospitalized patients with atrial fibrillation from the cardiology centre at FANN Hospital in Dakar. Tissue samples taken from each patient were sent to the laboratory and subjected to genetic analysis, which enabled the determination of the gene’s polymorphism, diversity, differentiation and genetic structure. The MTCYB gene amplification products obtained from the DNA extracts revealed a migration profile of a size estimated at approximately 1246 bp. All the non-synonymous mutations identified are implicated either in the structure and function of the protein, in its pathogenicity, or in its stability, and 15 of these were predicted by in silico tools to potentially affect all these aspects simultaneously. One of the synonymous mutations, m.15301G>A, which is thought to have no effect on protein stability, was found to be quite common in the population (14.54%) and is reported as a risk factor for high-altitude sickness. The functional and structural impact of the variants has been demonstrated, and four of them have effects that could alter the protein’s secondary structure through steric hindrance, the replacement of a proline in a cis position, and the replacement of a tyrosine (TYR > 6.3%) by a lysine (RSA < 20%) in a position deep within the hydrophobic core of cytochrome b. The MTCYB gene encodes cytochrome b, a central subunit of mitochondrial complex III involved in electron transport and proton translocation across the inner mitochondrial membrane. The variants identified in this case series may warrant further functional studies to determine whether they could contribute to mitochondrial dysfunction in the context of atrial fibrillation.
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