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Published on: May 21, 2010
Autosomal Recessive Spinocerebellar Ataxia Type 9 With a Response to Phosphate Repletion: A Case Report
Shotaro Haji1, Ryosuke Miyamoto1, Hiroyuki Morino1
1From the Department of Neurology (S.H., R.M., Y.O., Y.I.), Tokushima University Graduate School of Biomedical Sciences; Department of Clinical Neuroscience and Therapeutics (H.M.), Graduate School of Biomedical and Health Sciences; Department of Hematology (S.T., M.A.), Endocrinology and Metabolism, Tokushima University Graduate School of Biomedical Sciences; Department of Neuromuscular Research (I.N.), National Institute of Neuroscience, National Centre of Neurology and Psychiatry; and Department of Clinical Genome Analysis (I.N.), Medical Genome Center, National Center of Neurology and Psychiatry, Tokyo, Japan.
Objective:
Autosomal recessive spinocerebellar ataxia type 9 (SCAR9) has received attention due to its potential response to coenzyme Q10 (CoQ10) supplementation; however, the response has so far been limited and variable.
Methods:
We report a SCAR9 patient with severe hypophosphatemia who responded well to CoQ10 and phosphate repletion.
Results:
A 70-year-old man (the offspring of a consanguineous marriage) presented with cerebellar ataxia and intense fatigue after exercise. Whole-exome sequencing identified a novel homozygous deletion mutation (NM_020247.5:c.1218_1219del) in COQ8A. We thus diagnosed him with SCAR9. Supplementation of CoQ10 alleviated his symptoms, with the Scale for the Assessment and Rating of Ataxia (SARA) dropping from 16 to 14. During the course of the disease, he demonstrated continuous hypophosphatemia caused by renal phosphate wasting. Gait dysfunction due to weakness and eye movement was partially alleviated, and SARA dropped from 17 to 13 after phosphate repletion.
Discussion:
Phosphate repletion should be considered for patients with severe hypophosphatemia without any apparent subjective symptoms. In this case, phosphate repletion could have improved myopathy leading to partial improvement in the patient's symptoms. Further analyses regarding the association between COQ8A mutation and phosphate wasting are required to elucidate the detailed pathogenesis.
Classification Of Evidence:
This provides Class IV evidence. This is a single observational study without controls.
