A 4-year-old boy presented with subacute onset of cerebellar ataxia. Neuroimaging revealed cerebellar atrophy. Metabolic screening tests aiming to detect potentially treatable ataxias showed an increased value (fourfold upper limit of normal) for phytanic acid and elevated very-long-chain fatty acid (VLCFA) ratios (C24:0/C22:0 and C26:0/C22:0), while absolute concentrations of VLCFA were normal. Genetic analysis identified biallelic variants in PEX10. Immunohistochemistry confirmed pathogenicity in the patients' cultured fibroblasts demonstrating peroxisomal mosaicism with a general catalase import deficiency as well as conspicuous peroxisome morphology as an expression of impaired peroxisomal function. We describe for the first time an elongated peroxisome morphology in a patient with PEX10-related cerebellar ataxia.

A literature search yielded 14 similar patients from nine families with PEX10-related cerebellar ataxia, most of them presenting their first symptoms between 3 and 8 years of age. In 11/14 patients, the first and main symptom was cerebellar ataxia; in three patients, it was sensorineural hearing impairment. Finally, all 14 patients developed ataxia. Polyneuropathy (9/14) and cognitive impairment (9/14) were common associated findings. In 12/13 patients brain MRI showed cerebellar atrophy. Phytanic acid was elevated in 8/12 patients, while absolute concentrations of VLCFA levels were in normal limits in several patients. VLCFA ratios (C24:0/C22:0 and/or C26:0/C22:0), though, were elevated in 11/11 cases. We suggest including measurement of phytanic acid and VLCFA ratios in metabolic screening tests in unexplained autosomal recessive ataxias with cerebellar atrophy, especially when there is an early onset and symptoms are mild.

一名 4 岁男孩出现亚急性发作的小脑性共济失调。神经影像学显示小脑萎缩。旨在检测潜在可治疗共济失调的代谢筛查测试显示植烷酸值增加（正常上限的四倍）和超长链脂肪酸 (VLCFA) 比率升高（C24:0/C22:0 和 C26:0/C22 :0)，而 VLCFA 的绝对浓度正常。遗传分析确定了PEX10 中的双等位基因变体。免疫组织化学证实了患者培养的成纤维细胞的致病性，表明过氧化物酶体嵌合体具有一般的过氧化氢酶输入缺陷以及明显的过氧化物酶体形态作为过氧化物酶体功能受损的表现。我们首次在PEX10患者中描述了细长的过氧化物酶体形态-相关的小脑性共济失调。

文献检索得到来自 9 个PEX10家族的 14 名相似患者- 相关的小脑性共济失调，其中大多数在 3 至 8 岁之间出现首发症状。在 11/14 患者中，首发和主要症状是小脑性共济失调；三名患者是感音神经性听力障碍。最后，所有 14 名患者均出现共济失调。多发性神经病 (9/14) 和认知障碍 (9/14) 是常见的相关发现。在 12/13 名患者中，脑部 MRI 显示小脑萎缩。8/12 患者的植烷酸升高，而几名患者的 VLCFA 绝对浓度处于正常范围内。然而，VLCFA 比率（C24:0/C22:0 和/或 C26:0/C22:0）在 11/11 病例中升高。我们建议在不明原因的常染色体隐性共济失调伴小脑萎缩的代谢筛查试验中包括植烷酸和 VLCFA 比率的测量，