Primary CoQ10 deficiency with a severe phenotype due to the c.901 C > T (p.R301W) mutation in the COQ8A gene

PURPOSE

A patient with primary CoQ10 deficiency associated with the c.901 C > T (p.R301W) (rs140246430) homozygous missense pathogenic variant in the COQ8A gene, who presented with recurrent status epilepticus, stroke-like lesions, and hypertrophic cardiomyopathy while being followed-up with early-onset autosomal recessive cerebellar ataxia will be reported in this article.

CASE REPORT

A 16-year-old patient who was being followed up at an external center with a diagnosis of ataxia with cerebellar atrophy had been seen 3 different times within a year for status epilepticus. The cerebral MRI showed severe cerebellar atrophy, stroke like lesions, and an inverted double- lactate peak on spectroscopy. Her echocardiography revealed marked left ventricular hypertrophy. Mitochondrial cocktail therapy containing a standard dose of CoQ10 was started, considering mitochondrial disease. The patient died due to cardiomyopathy. Mitochondrial panel analysis revealed the presence of the c.901 C > T (p.R301W) homozygous missense mutation in the COQ8A gene.

CONCLUSIONS

Primary Coenzyme Q10 deficiency should be considered in patients presenting with autosomal recessive stable-appearing progressive ataxia, emerging attacks of status epilepticus, stroke-like lesions on neuroimaging, and cardiomyopathy. Since there is a case with the same mutation with a similar fatal course in the literature, detection of c.901 C > T (p.R301W) mutation homozygously should be a warning for a severe prognosis and more aggressive treatment should be started without delay with a high dose of CoQ10 instead of the lower doses used in the treatment of mitochondrial disease.

Adolescence Onset Primary Coenzyme Q10 Deficiency With Rare CoQ8A Gene Mutation: A Case Report and Review of Literature

Background

Primary deficiency of coenzyme Q₁₀ deficiency-4 (CoQ₁₀D4) is a heterogeneous disorder affecting different age groups. The main clinical manifestation consists of cerebellar ataxia, exercise intolerance, and dystonia.

Case report

We provide a case of adolescence-onset ataxia, head tremor, and proximal muscle weakness accompanied by psychiatric features and abnormal serum urea (49.4 mg/dL), lactate (7.5 mmol/L), and CoQ10 level (0.4 µg/mL). Brain-MRI demonstrated cerebellar atrophy, thinning of the corpus callosum, and loss of white matter. Whole exome sequencing showed a homozygous missense mutation (c.911C>T; p.A304V) in CoQ8A gene which is a rare mutation and responsible variant of CoQ₁₀D4. After supplementary treatment with CoQ₁₀ 50 mg/twice a day for 2 months the clinical symptoms improved.

Conclusion

These observations highlight the significance of the early diagnosis of potentially treatable CoQ8A mutation as well as patient education and follow-up. Our findings widen the spectrum of CoQ8A phenotypic features so that clinicians be familiar with the disease not only in severe childhood-onset ataxia but also in adolescence with accompanying psychiatric problems.

The cerebellar bioenergetic state predicts treatment response in COQ8A-related ataxia

INTRODUCTION

Primary coenzyme Q10 (CoQ10) deficiency, a recessive disorder associated with various defects of CoQ10 biosynthesis and widely varying clinical presentation, is customarily managed by oral Q10 supplementation but the benefit is debated.

METHODS

To address this question, we mapped individual responses in two patients with COQ8A-related ataxia following coenzyme Q10 supplementation using noninvasive imaging. Metabolic ³¹phosphorus magnetic resonance spectroscopy imaging (³¹P-MRSI) and volumetric cerebellar neuroimaging were performed to quantify the individual treatment response in two patients with COQ8A-related ataxia, each compared with eight age- and gender-matched healthy control subjects.

RESULTS

Post-treatment change in energy metabolite levels differed in the two patients, with higher energy levels and improved dysarthria and leg coordination in one, and decreased energy levels without clinical benefit in the other.

CONCLUSIONS

Our results suggest that the cerebellar bioenergetic state may predict treatment response in COQ8A-related ataxia and highlight the potential of pathophysiology-orientated neuroimaging evidence to inform treatment decisions.

Epilepsia Partialis Continua a Clinical Feature of a Missense Variant in the ADCK3 Gene and Poor Response to Therapy

Introduction

Coenzyme Q10 deficiency can be due to mutations in Coenzyme Q10-biosynthesis genes (primary) or genes unrelated to biosynthesis (secondary). Primary Coenzyme Q10 deficiency-4 (COQ10D4), also known as autosomal recessive spinocerebellar ataxia-9 (SCAR9), is an autosomal recessive disorder caused by mutations in the ADCK3 gene. This disorder is characterized by several clinical manifestations such as severe infantile multisystemic illness, encephalomyopathy, isolated myopathy, cerebellar ataxia, or nephrotic syndrome.

Methods

In this study, whole-exome sequencing was performed in order to identify disease-causing variants in an affected girl with developmental regression and Epilepsia Partialis Continua (EPC). Next, Sanger sequencing method was used to confirm the identified variant in the patient and segregation analysis in her parents.

Case Presentation

The proband is an affected 11-year-old girl with persistent seizures, EPC, and developmental regression including motor, cognition, and speech. Seizures were not controlled with various anticonvulsant drugs despite adequate dosing. Progressive cerebellar atrophy, stroke-like cortical involvement, multifocal hyperintense bright objects, and restriction in diffusion-weighted imaging (DWI) were seen in the brain magnetic resonance imaging (MRI).

Conclusions

A novel homozygous missense variant [NM_020247.5: c.814G>T; (p.Gly272Cys)] was identified within the ADCK3 gene, which is the first mutation in this gene in the Iranian population. Bioinformatics analysis showed this variant is damaging. Based on our patient, clinicians should consider genetic testing earlier to instant diagnosis and satisfactory treatment based on exact etiology to prevent further neurologic sequelae.

One-year outcome of coenzyme Q10 supplementation in ADCK3 ataxia (ARCA2)

Background

The recessive ataxia ARCA2 is a rare disorder characterized by Coenzyme Q10 (CoQ10) deficiency due to biallelic mutations in ADCK3 gene. Despite the pathophysiological role, available data are not univocal on clinical efficacy of CoQ10 supplementation in ARCA2. Here we described the long-term motor outcome of 4 untreated ARCA2 patients prospectively followed-up for one year after starting CoQ10 oral supplementation (15 mg/kg/day).

Methods

Clinical rating scales (SARA; 9 holes peg test; 6 min walking test; Timed 25-Foot Walk) and videoelectronic gait analysis were performed at baseline and every 6 months (T0, T1, T2) to evaluate the motor performances. Since two patients discontinued the treatment at the 7th month, we could provide comparative analysis between longer and shorter supplementation.

Results

At T2, the gait speed (Timed 25-Foot Walk test) significantly differed between patients with long and short treatment; overall, the clinical condition tended to be better in patients continuing CoQ10.

Conclusions

Although preliminarily, this observation suggests that only prolonged and continuous CoQ10 supplementation may induce mild clinical effects on general motor features of ARCA2. Dedicated trials are now necessary to extend and validate such observation.

Primary Coenzyme Q deficiency Due to Novel ADCK3 Variants, Studies in Fibroblasts and Review of Literature

Primary deficiency of coenzyme Q10 (CoQ10 ubiquinone), is classified as a mitochondrial respiratory chain disorder with phenotypic variability. The clinical manifestation may involve one or multiple tissue with variable severity and presentation may range from infancy to late onset. ADCK3 gene mutations are responsible for the most frequent form of hereditary CoQ10 deficiency (Q10 deficiency-4 OMIM #612016) which is mainly associated with autosomal recessive spinocerebellar ataxia (ARCA2, SCAR9). Here we provide the clinical, biochemical and genetic investigation for unrelated three nuclear families presenting an autosomal form of Spino-Cerebellar Ataxia due to novel mutations in the ADCK3 gene. Using next generation sequence technology we identified a homozygous Gln343Ter mutation in one family with severe, early onset of the disease and compound heterozygous mutations of Gln343Ter and Ser608Phe in two other families with variable manifestations. Biochemical investigation in fibroblasts showed decreased activity of the CoQ dependent mitochondrial respiratory chain enzyme succinate cytochrome c reductase (complex II + III). Exogenous CoQ slightly improved enzymatic activity, ATP production and decreased oxygen free radicals in some of the patient's cells. Our results are presented in comparison to previously reported mutations and expanding the clinical, molecular and biochemical spectrum of ADCK3 related CoQ10 deficiencies.

Cerebellar ataxia and severe muscle CoQ10 deficiency in a patient with a novel mutation in ADCK3

Inherited ataxias are a group of heterogeneous disorders in children or adults but their genetic definition remains still undetermined in almost half of the patients. However, CoQ10 deficiency is a rare cause of cerebellar ataxia and ADCK3 is the most frequent gene associated with this defect. We herein report a 48 year old man, who presented with dysarthria and walking difficulties. Brain magnetic resonance imaging showed a marked cerebellar atrophy. Serum lactate was elevated. Tissues obtained by muscle and skin biopsies were studied for biochemical and genetic characterization. Skeletal muscle biochemistry revealed decreased activities of complexes I+III and II+III and a severe reduction of CoQ10 , while skin fibroblasts showed normal CoQ10 levels. A mild loss of maximal respiration capacity was also found by high-resolution respirometry. Molecular studies identified a novel homozygous deletion (c.504del_CT) in ADCK3, causing a premature stop codon. Western blot analysis revealed marked reduction of ADCK3 protein levels. Treatment with CoQ10 was started and, after 1 year follow-up, patient neurological condition slightly improved. This report suggests the importance of investigating mitochondrial function and, in particular, muscle CoQ10 levels, in patients with adult-onset cerebellar ataxia. Moreover, clinical stabilization by CoQ10 supplementation emphasizes the importance of an early diagnosis.

Preparation and characterization of human ADCK3, a putative atypical kinase

AarF domain containing kinase 3 (ADCK3) is a mitochondrial protein known to have a role in the electron transport chain. Despite being required for the biosynthesis of coenzyme Q10, a lipid-soluble electron transporter found to be essential for aerobic cellular respiration, the precise biological function of ADCK3 remains unknown. Patients with mutations in ADCK3 experience an onset of neurological disorders from childhood, including cerebellar ataxia and exercise intolerance. After extensive screening for soluble recombinant protein expression, an N-terminal fusion of maltose-binding protein was found to facilitate the overexpression of the human ADCK3 kinase domain in Escherichia coli as a soluble and biologically active entity. For the first time our work reveals Mg(2+)-dependent ATPase activity of ADCK3, providing strong support for the theoretical prediction of this protein being a functional atypical kinase.