BACKGROUND Biotinidase deficiency (BTD) is an autosomal recessive inborn error of metabolism provoking progressive biotin depletion, which causes, in turn, multiple carboxylase deficiency. Its infantile onset is characterized by intractable seizures associated with lethargy, psychomotor regression, hypotonia, feeding and respiratory problems, and cutaneous abnormalities. CASE DESCRIPTION We describe a 52-month-old female whose clinical and neuroradiological pictures were consistent with myelopathy, which is generally more frequent in older patients, as well as with symptoms of an infantile onset of biotinidase deficiency, revealed at 17 months. RESULTS A biochemical biotinidase test revealed a profound deficiency of biotinidase detecting a 10% residual enzymatic activity, which led to the diagnosis of BTD. Gene sequencing revealed a compound heterozigous mutation (c.454A > C/c.1612C > T). CONCLUSION Our findings suggest that even if myelopathy is uncommonly reported in BTD, and generally occurs in older children, its presence in childhood-onset floppiness should always be considered as a possible marker for an atypical presentation of BTD. Although, until recently, BTD myelopathy was believed to be prevalent in older children, a spinal cord involvement has also been described in at least nine cases in early infancy. Thus, another early diagnosis suggests that myelopathy may be more frequent than previously thought, and it is probably underdiagnosed because spinal MRI is not always routinely performed on these children. Early recognition of BTD disease is important as it would lead to prompt treatment, preventing irreversible brain damage and increasing the chances of complete recovery.

中文翻译：

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儿童脊髓脱髓鞘：神经儿科获得良好结果的诊断挑战

背景生物素酶缺乏症（BTD）是一种常染色体隐性先天性代谢缺陷，引起进行性生物素耗竭，进而导致多种羧化酶缺乏症。其婴儿期发作的特征是与嗜睡、精神运动退化、张力减退、喂养和呼吸问题以及皮肤异常相关的顽固性癫痫发作。病例描述 我们描述了一名 52 个月大的女性，其临床和神经放射学图片与脊髓病一致，这通常在老年患者中更常见，并且在 17 个月时出现婴儿期生物素酶缺乏症的症状。结果 生化生物素酶测试显示生物素酶严重缺乏，检测到 10% 的残留酶活性，这导致了 BTD 的诊断。基因测序显示复合杂合突变（c.454A > C/c.1612C > T）。结论 我们的研究结果表明，即使骨髓病在 BTD 中不常见，并且通常发生在年龄较大的儿童中，但其在儿童期发作的松软中的存在应始终被视为 BTD 非典型表现的可能标志。虽然直到最近，人们认为 BTD 脊髓病在年龄较大的儿童中普遍存在，但在婴儿早期至少有 9 例脊髓受累。因此，另一个早期诊断表明脊髓病可能比以前认为的更频繁，并且可能未被诊断出来，因为这些儿童并不总是定期进行脊柱 MRI 检查。早期识别 BTD 疾病很重要，因为它会导致及时治疗，