Hammoud Miloud, Domínguez-Ruiz María, Assiri Imane, Rodrigues Daniel, Aboussair Nisrine, Lanza Val F, Villarrubia Jesús, Colón Cristóbal, Fdil Naima, Del Castillo Francisco J
Metabolic Platform, Biochemistry Laboratory, Team for Childhood, Health and Development, Faculty of Medicine, Cadi Ayyad University, Marrakech B.P. 7010, Morocco.
Moroccan Association for Inherited Metabolic Diseases, Morocco.
Genes (Basel). 2024 Nov 26;15(12):1515. doi: 10.3390/genes15121515.
(1) Background: Most rare disease patients endure long delays in obtaining a correct diagnosis, the so-called "diagnostic odyssey", due to a combination of the rarity of their disorder and the lack of awareness of rare diseases among both primary care professionals and specialists. Next-generation sequencing (NGS) techniques that target genes underlying diverse phenotypic traits or groups of diseases are helping reduce these delays; (2) Methods: We used a combination of biochemical (thin-layer chromatography and high-performance liquid chromatography-tandem mass spectrometry), NGS (resequencing gene panels) and splicing assays to achieve a complete diagnosis of three patients with suspected metachromatic leukodystrophy, a neurologic lysosomal disorder; (3) Results: Affected individuals in each family were homozygotes for harmful variants in the gene, one of them novel (c.854+1dup, in family 1) and the other already described (c.640G>A, p.(Ala214Thr), in family 2). In addition, both affected individuals in family 2 were carriers of a known pathogenic variant in an additionallysosomal disease gene, (for mucolipidosis III). This additional variant may modify the clinical presentation by increasing lysosomal dysfunction. (4) Conclusions: We demonstrated the deleterious effect of the novel variant c.854+1dup on the splicing of transcripts. We also confirmed the involvement of variant c.640G>A in metachromatic leukodystrophy. Our results show the power of diagnostic approaches that combine deep phenotyping, NGS, and biochemical and functional techniques.
(1) 背景：大多数罕见病患者由于其所患疾病的罕见性以及基层医疗专业人员和专科医生对罕见病缺乏认识，在获得正确诊断方面经历了长时间的延误，即所谓的“诊断之旅”。针对多种表型特征或疾病组潜在基因的新一代测序（NGS）技术有助于减少这些延误；(2) 方法：我们结合使用了生化方法（薄层色谱法和高效液相色谱 - 串联质谱法）、NGS（重测序基因 panel）和剪接分析，以对三名疑似异染性脑白质营养不良（一种神经溶酶体疾病）的患者进行完整诊断；(3) 结果：每个家庭中的受影响个体均为该基因有害变异的纯合子，其中一个是新发现的变异（家系 1 中的 c.854+1dup），另一个是已报道的变异（家系 2 中的 c.640G>A，p.(Ala214Thr)）。此外，家系 2 中的两名受影响个体均为另一种溶酶体疾病基因（用于黏脂贮积症 III）中已知致病变异的携带者。这种额外的变异可能通过增加溶酶体功能障碍来改变临床表现。(4) 结论：我们证明了新变异 c.854+1dup 对该转录本剪接的有害影响。我们还证实了变异 c.640G>A 与异染性脑白质营养不良有关。我们的结果显示了结合深度表型分析、NGS 以及生化和功能技术的诊断方法的强大作用。
