Abstract：
Metachromatic leukodystrophy (MLD) is a rare hereditary neurodegenerative disease caused by deficiency of the lysosomal enzyme arylsulfatase A (ARSA). This study described the clinical and molecular characteristics of 24 Chinese children with MLD and investigated functional characterization of five novel ARSA variants. A retrospective analysis was performed in 24 patients diagnosed with MLD at Guangzhou Women and Children\'s Medical Center in South China. Five novel mutations were further characterized by transient expression studies. We recruited 17 late-infantile, 3 early-juvenile, 4 late-juvenile MLD patients. In late-infantile patients, motor developmental delay and gait disturbance were the most frequent symptoms at onset. In juvenile patients, cognitive regression and gait disturbance were the most frequent chief complaints. Overall, 25 different ARSA mutations were identified with 5 novel mutations.The most frequent alleles were p.W320* and p.G449Rfs. The mutation p.W320*, p.Q155=, p.P91L, p.G156D, p.H208Mfs*46 and p.G449Rfs may link to late-infantile type. The novel missense mutations were predicted damaging in silico. The bioinformatic structural analysis of the novel missense mutations showed that these amino acid replacements would cause severe impairment of protein structure and function. In vitro functional analysis of the six mutants, showing a low ARSA enzyme activity, clearly demonstrated their pathogenic nature. The mutation p.D413N linked to R alleles. In western blotting analysis of the ARSA protein, the examined mutations retained reduced amounts of ARSA protein compared to the wild type. This study expands the spectrum of genotype of MLD. It helps to the future studies of genotype-phenotype correlations to estimate prognosis and develop new therapeutic approach.
摘要：
异染性脑白质营养不良（MLD）是一种罕见的遗传性神经退行性疾病，由溶酶体酶芳基硫酸酯酶A（ARSA）的缺乏引起。这项研究描述了24例MLD中国儿童的临床和分子特征，并研究了五种新型ARSA变体的功能特征。方法对华南地区广州市妇女儿童医疗中心24例诊断为MLD的患者进行回顾性分析。通过瞬时表达研究进一步表征了五个新的突变。我们招募了17名晚期婴儿，3早期少年，4名青少年晚期MLD患者。在晚期婴儿患者中，运动发育迟缓和步态障碍是发病时最常见的症状。在青少年患者中，认知回归和步态障碍是最常见的主诉.总的来说,25种不同的ARSA突变被鉴定为具有5种新突变。最常见的等位基因是p.W320*和p.G449Rfs。突变p.W320*,p.Q155=,p.P91L,p.G156D,p.H208Mfs*46和p.G449Rfs可能与婴儿晚期类型相关。预测新的错义突变在计算机上具有破坏性。新型错义突变的生物信息学结构分析表明，这些氨基酸替换会导致蛋白质结构和功能的严重损害。6个突变体的体外功能分析,显示低ARSA酶活性，清楚地证明了它们的致病性。突变p.D413N与R等位基因相关。在ARSA蛋白的蛋白质印迹分析中，与野生型相比,所检查的突变保留了减少量的ARSA蛋白.这项研究扩展了MLD的基因型谱。它有助于未来基因型-表型相关性的研究，以估计预后和开发新的治疗方法。
