Oka Nobuyuki
Department of Neurology, National Hospital Organization Minami-Kyoto Hospital.
Brain Nerve. 2016 Jan;68(1):21-9. doi: 10.11477/mf.1416200342.
Although genetic testing is available, nerve biopsy is useful in selected patients for the diagnosis of Charcot-Marie-Tooth disease (CMT). These are sporadic cases of hereditary neuropathy, or familial cases in which genetic testing is negative. CMT is caused by mutations of various genes. The pathological features of CMT have mostly been investigated using nerve biopsy, which may shed light on the presumed functions of mutated gene products. PMP22 duplication in CMT1A induces numerous large onion bulb lesions (OB). Compared to chronic inflammatory demyelinating polyradiculoneuropathy, the differential features of CMT1A are patchy distribution of OB and non-inflammatory lesions. CMT1B also manifests as OB, but presents abnormal compaction of myelin sheaths caused by uncompacted myelin or excessive myelin folding. CMT2 includes axonal neuropathies and many causative genes have been found. CMT2A (MFN2 mutation) shows abnormal mitochondria with a spherical morphology instead of tubular in the longitudinal direction. CMT4 consists of autosomal recessive forms with demyelinating pathology. Most subtypes have mutations of genes relating to myelin maintenance, and pathologically, they show abnormal folding of the myelin structure.
尽管可以进行基因检测，但神经活检对于某些诊断遗传性运动感觉神经病（CMT）的患者仍很有用。这些患者包括遗传性神经病的散发病例，或基因检测呈阴性的家族性病例。CMT由多种基因突变引起。CMT的病理特征大多通过神经活检进行研究，这可能有助于了解突变基因产物的假定功能。CMT1A中的PMP22重复会导致大量大的洋葱球样病变（OB）。与慢性炎症性脱髓鞘性多发性神经根神经病相比，CMT1A的鉴别特征是OB和非炎症性病变的斑片状分布。CMT1B也表现为OB，但呈现由髓鞘疏松或髓鞘过度折叠引起的髓鞘异常致密化。CMT2包括轴索性神经病，并且已经发现了许多致病基因。CMT2A（MFN2突变）显示线粒体异常，呈球形而非纵向的管状形态。CMT4由具有脱髓鞘病理的常染色体隐性形式组成。大多数亚型具有与髓鞘维持相关的基因突变，并且在病理上，它们表现出髓鞘结构的异常折叠。
