COQ4 and cardiomyopathy: Sondheimer et al. [51] described an infant with seizures and cardiomyopathy dying in early infancy, resulting from a deletion ([c.23_33del11] [p. Val8AlafsX19]), and two missense mutations ([c.331G>T] [p. Asp111Tyr] and [c.356C>T] [p.Pro119Leu]) in the COQ4 gene.