Articles

Compound heterozygous inheritance of two novel COQ2 variants results in familial coenzyme Q deficiency

Abdelhakim, Aliaa H.; Dharmadhikari, Avinash V.; Ragi, Sara D.; de Carvalho, Jose R. L.; Xu, Christine L.; Thomas, Amanda L.; Buchovecky, Christie M.; Mansukhani, Mahesh M.; Naini, Ali B.; Liao, Jun; Jobanputra, Vaidehi; Maumenee, Irene H.; Tsang, Stephen H.

Background
Primary coenzyme Q10 deficiency is a rare disease that results in diverse and variable clinical manifestations. Nephropathy, myopathy and neurologic involvement are commonly associated, however retinopathy has also been observed with certain pathogenic variants of genes in the coenzyme Q biosynthesis pathway. In this report, we describe a novel presentation of the disease that includes nephropathy and retinopathy without neurological involvement, and which is the result of a compound heterozygous state arising from the inheritance of two recessive potentially pathogenic variants, previously not described.


Materials and methods
Retrospective report, with complete ophthalmic examination, multimodal imaging, electroretinography, and whole exome sequencing performed on a family with three affected siblings.


Results
We show that affected individuals in the described family inherited two heterozygous variants of the COQ2 gene, resulting in a frameshift variant in one allele, and a predicted deleterious missense variant in the second allele (c.288dupC,p.(Ala97Argfs*56) and c.376C > G,p.(Arg126Gly) respectively). Electroretinography results were consistent with rod-cone dystrophy in the affected individuals. All affected individuals in the family exhibited the characteristic retinopathy as well as end-stage nephropathy, without evidence of any neurological involvement.


Conclusions
We identified two novel compound heterozygous variants of the COQ2 gene that result in primary coenzyme Q deficiency. Targeted sequencing of coenzyme Q biosynthetic pathway genes may be useful in diagnosing oculorenal clinical presentations syndromes not explained by more well known syndromes (e.g., Senior-Loken and Bardet-Biedl syndromes).

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Also Published In

Title
Orphanet Journal of Rare Diseases
DOI
https://doi.org/10.1186/s13023-020-01600-8

More About This Work

Published Here
August 10, 2022

Notes

Coenzyme Q10, COQ2 gene, Oculorenal syndrome, Hereditary retinopathy