Takanashi Jun-Ichi
Department of Pediatrics, Tokyo Women's Medical University Yachiyo Medical Center, 477-96 Owadashinden, Yachiyo-Shi, Chiba 276-8524, Japan.
Brain Dev. 2025 Jun;47(3):104345. doi: 10.1016/j.braindev.2025.104345. Epub 2025 Apr 1.
Recent advancements in molecular biology and radiology have led to the identification of several new leukodystrophies. A key diagnostic feature of leukodystrophies is the increased white matter signal intensity observed on T2-weighted magnetic resonance (MR) images. Leukodystrophies are typically classified into two main categories: hypomyelinating leukodystrophies (HLD) and other forms, including demyelinating leukodystrophies. HLD is characterized by a primary defect in myelin due to genetic variants that affect structural myelin proteins, oligodendrocyte transcription factors, RNA translation, and lysosomal proteins. Radiologically, HLD tends to show less pronounced white matter hyperintensity on T2-weighted images than demyelinating leukodystrophies. A definitive diagnosis can often be made by identifying abnormalities in regions beyond the white matter, such as the basal ganglia or cerebellum, or through the presence of characteristic clinical symptoms. N-acetylaspartate, a neuroaxonal marker observed on MR spectroscopy, is typically reduced in many neurological conditions, but N-acetylaspartate levels often remain normal in HLD, which is considered a distinctive feature of this disorder. This article provides an overview of the latest imaging findings and clinical features associated with HLD.
分子生物学和放射学的最新进展已促使人们识别出几种新的脑白质营养不良症。脑白质营养不良症的一个关键诊断特征是在T2加权磁共振（MR）图像上观察到白质信号强度增加。脑白质营养不良症通常分为两大类：低髓鞘形成性脑白质营养不良症（HLD）和其他类型，包括脱髓鞘性脑白质营养不良症。HLD的特征是由于影响结构性髓鞘蛋白、少突胶质细胞转录因子、RNA翻译和溶酶体蛋白的基因变异导致髓鞘出现原发性缺陷。在放射学上，与脱髓鞘性脑白质营养不良症相比，HLD在T2加权图像上的白质高信号往往不太明显。通过识别白质以外区域（如基底神经节或小脑）的异常情况，或通过特征性临床症状的存在，通常可以做出明确诊断。N-乙酰天门冬氨酸是在磁共振波谱上观察到的一种神经轴突标记物，在许多神经系统疾病中通常会降低，但在HLD中N-乙酰天门冬氨酸水平往往保持正常，这被认为是该疾病的一个显著特征。本文概述了与HLD相关的最新影像学发现和临床特征。
