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JIMD Rep. 2018;42:31-36. doi: 10.1007/8904_2017_73. Epub 2017 Nov 21.

Compound Heterozygous Inheritance of Mutations in Coenzyme Q8A Results in Autosomal Recessive Cerebellar Ataxia and Coenzyme Q10 Deficiency in a Female Sib-Pair.

Author information

1
Centre for Brain Research, School of Biological Sciences, The University of Auckland, Auckland, New Zealand.
2
Genetic Health Service New Zealand, Auckland City Hospital, Auckland, New Zealand.
3
Diagnostic Genetics, LabPLUS, Auckland City Hospital, Auckland, New Zealand.
4
Department of Neurology, Auckland City Hospital, Auckland, New Zealand.
5
Canterbury Health Laboratories, Christchurch, New Zealand.
6
Dunedin School of Medicine, University of Otago, Dunedin, New Zealand.
7
Centre for Brain Research, School of Biological Sciences, The University of Auckland, Auckland, New Zealand. r.snell@auckland.ac.nz.

Abstract

Autosomal recessive ataxias are characterised by a fundamental loss in coordination of gait with associated atrophy of the cerebellum. There is significant clinical and genetic heterogeneity amongst inherited ataxias; however, an early molecular diagnosis is essential with low-risk treatments available for some of these conditions. We describe two female siblings who presented early in life with unsteady gait and cerebellar atrophy. Whole exome sequencing revealed compound heterozygous inheritance of two pathogenic mutations (p.Leu277Pro, c.1506+1G>A) in the coenzyme Q8A gene (COQ8A), a gene central to biosynthesis of coenzyme Q (CoQ). The paternally derived p.Leu277Pro mutation is predicted to disrupt a conserved motif in the substrate-binding pocket of the protein, resulting in inhibition of CoQ10 production. The maternal c.1506+1G>A mutation destroys a canonical splice donor site in exon 12 affecting transcript processing and subsequent protein translation. Mutations in this gene can result in primary coenzyme Q10 deficiency type 4, which is characterized by childhood onset of cerebellar ataxia and exercise intolerance, both of which were observed in this sib-pair. Muscle biopsies revealed unequivocally low levels of CoQ10, and the siblings were subsequently established on a therapeutic dose of CoQ10 with distinct clinical evidence of improvement after 1 year of treatment. This case emphasises the importance of an early and accurate molecular diagnosis for suspected inherited ataxias, particularly given the availability of approved treatments for some subtypes.

KEYWORDS:

Autosomal recessive cerebellar ataxia; COQ8A; CoQ10

PMID:
29159460
DOI:
10.1007/8904_2017_73

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