A homozygous splice variant in ATP5PO, disrupts mitochondrial complex V function and causes Leigh syndrome in two unrelated families.

Mitochondrial complex V plays an important role in oxidative phosphorylation by catalyzing the generation of ATP. Most complex V subunits are nuclear encoded and not yet associated with recognized Mendelian disorders. Using exome sequencing, we identified a rare homozygous splice variant (c.87+3A>G) in ATP5PO, the complex V subunit which encodes the oligomycin sensitivity conferring protein, in three individuals from two unrelated families, with clinical suspicion of a mitochondrial disorder. These individuals had a similar, severe infantile and often lethal multi-systemic disorder that included hypotonia, developmental delay, hypertrophic cardiomyopathy, progressive epileptic encephalopathy, progressive cerebral atrophy, and white matter abnormalities on brain MRI consistent with Leigh syndrome. cDNA studies showed a predominant shortened transcript with skipping of exon 2 and low levels of the normal full-length transcript. Fibroblasts from the affected individuals demonstrated decreased ATP5PO protein, defective assembly of complex V with markedly reduced amounts of peripheral stalk proteins, and complex V hydrolytic activity. Further, expression of human ATP5PO cDNA without exon 2 (hATP5PO-∆ex2) in yeast cells deleted for yATP5 (ATP5PO homolog) was unable to rescue growth on media which requires oxidative phosphorylation when compared to the wild type construct (hATP5PO-WT), indicating that exon 2 deletion leads to a non-functional protein. Collectively, our findings support the pathogenicity of the ATP5PO c.87+3A>G variant, which significantly reduces but does not eliminate complex V activity. These data along with the recent report of an affected individual with ATP5PO variants, add to the evidence that rare biallelic variants in ATP5PO result in defective complex V assembly, function and are associated with Leigh syndrome. © 2022 SSIEM.

Citation

Mythily Ganapathi, Gaelle Friocourt, Naig Gueguen, Marisa W Friederich, Gerald Le Gac, Volkan Okur, Nadège Loaëc, Thomas Ludwig, Chandran Ka, Kurenai Tanji, Pascale Marcorelles, Evangelos Theodorou, Angela Lignelli-Dipple, Cécile Voisset, Melissa A Walker, Lauren C Briere, Amélie Bourhis, Marc Blondel, Charles LeDuc, Jacob Hagen, Cathleen Cooper, Colleen Muraresku, Claude Ferec, Armelle Garenne, Servane Lelez-Soquet, Cassandra A Rogers, Yufeng Shen, Dana K Strode, Peyman Bizargity, Alejandro Iglesias, Amy Goldstein, Frances A High, Undiagnosed Diseases Network, David A Sweetser, Rebecca Ganetzky, Johan L K Van Hove, Vincent Procaccio, Cedric Le Marechal, Wendy K Chung. A homozygous splice variant in ATP5PO, disrupts mitochondrial complex V function and causes Leigh syndrome in two unrelated families. Journal of inherited metabolic disease. 2022 Sep;45(5):996-1012

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PMID: 35621276

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