Mitochondrial complex III deficiencies in the newborn infant

New mechanisms for respiratory chain complex III diseases have recently been reported. Deletions, rearrangements and tRNA mutations of mitochondrial DNA cause deficiencies in several complexes. Mutations in the only complex III subunit encoded by mitochondrial DNA, cytochrome b, cause variable clinical phenotypes, such as cardiomyopathy or multisystemic dysfunction after birth. The homozygous serine78alanine mutation in the complex III assembling protein, BCS1L, causes a distinct phenotype, the GRACILE syndrome, whereas in other BCS1L mutations, the clinical picture is variable, but tubulopathy and liver dysfunction are typical.

Section editor:Vineta Fellman – Division of Pediatrics, Lund University, Lund, Sweden