Objective: To present the first reported Colombian case in a patient presenting COQ8A-ataxia with bilateral palpebral ptosis, who had a favorable response to CoQ10 supplementation after a 57-year diagnostic delay.

Background: COQ8A-ataxia is a rare autosomal recessive disorder characterized by early-onset slowly-progressive ataxia, which may be accompanied by epilepsy, and dystonia. It results from biallelic pathogenic loss-of-function variants in the COQ8A gene, which encodes a mitochondrial atypical kinase/ATPase essential for the integrity of the coenzyme Q10 (CoQ10) biosynthetic complex.

Method: A 67-year-old woman presented with progressive ataxia. Her symptoms began at age 10 with gait instability, dysarthria, and falls. Bilateral palpebral ptosis developed soon after. No significant medical history. Her parents were first cousins.

She exhibited bilateral palpebral ptosis, bilateral hypometric saccades, dysmetria, and dysdiadochokinesia. Her gait was ataxic. Reflexes were normal, with no abnormal movements or upper motor neuron signs.

Brain MRI revealed severe cerebellar atrophy (Figure 1). Initial laboratory tests were normal. Electromyography showed no abnormalities. A panel for spinocerebellar ataxias (1, 2, 3, 6, 7, 8, 10, 17) was negative. A broader ataxia panel identified a homozygous pathogenic variant in the COQ8A gene (NM_020247.4: c.1358del p.Leu453Argfs24*), consistent with autosomal recessive cerebellar ataxia due to primary coenzyme Q10 deficiency type 4. Treatment with CoQ10 supplementation was initiated, resulting in significant improvement (SARA: 8, previous 24).

Results: Discussion

COQ8A-ataxia is the most common form of primary CoQ10 deficiency. Its prevalence remains unknown; however, approximately 123 cases have been reported worldwide. We present the first case in Colombia, characterized by pure cerebellar ataxia and bilateral palpebral ptosis. The latter is an uncommon feature among reported cases and is more common in SCA28 and POLG-related disorders.

Our patient falls within the subset of individuals with favorable response to CoQ10 (50%) despite a 57-year diagnostic delay.

Conclusion: COQ8A-ataxia should be considered an important differential diagnosis in cases of slowly progressive childhood-onset cerebellar ataxia, both with and without additional clinical features. Timely diagnosis is crucial, as this disorder is treatable, and symptoms are potentially reversible with appropriate intervention.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-unlikely-treatable-a-case-of-ataxia/