Doctorado en Genética Humana, Centro Universitario Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, México.
Laboratorio de Diagnóstico Bioquímico de Enfermedades Lisosomales, División de Genética, Centro de Investigación Biomédica de Occidente (CIBO), Instituto Mexicano del Seguro Social (IMSS), Guadalajara, México.
Mol Genet Genomic Med. 2020 Aug;8(8):e1305. doi: 10.1002/mgg3.1305. Epub 2020 May 19.
Metachromatic Leukodystrophy (MLD, OMIM 250100) is a neurodegenerative disease caused by mutations in the ARSA gene (OMIM 607574) that lead to deficiency in Arylsulfatase A (ASA). ASA pseudodeficiency (PD-ASA) is a biochemical condition that substantially diminishes ASA activity but is not associated with clinical manifestations. PD-ASA is associated with the c.1055A>G (p.Asn352Ser) (rs2071421) and c.*96A>G (rs6151429) variants, which have an estimated frequency of 2% in the population.
To determine the activity of Arylsulfatase A and to identify variants and haplotypes in the ARSA gene in Mexican individuals with pseudodeficiency.
Two-hundred apparently healthy individuals were included to determine the enzymatic activity of ASA in leukocytes by spectrophotometric analysis, and identification of the PD-ASA alleles was performed by PCR-RFLP assays. Genotypes were confirmed by semi-automated Sanger sequencing. Haplotypes were constructed using Arlequin v.10.04, and linkage disequilibrium analysis was performed with Cube X.
The enzymatic activity of ASA was determined to be 1.74-2.09 nmol/mg protein/min and later correlated with genotypes and haplotypes. For the (p.Asn352Ser) variant, we found 126 (0.63) individuals with the AA genotype, 62 with AG (0.31) and 12 with GG (0.06); the frequency of the polymorphic allele was 0.215 (86 alleles, 21.5%), and the variant was in HWE (p = .2484). The variant c.*96A>G was also in HWE (p = .2105): 185 individuals (0.925) with the AA genotype, 14 (0.07) with AG, and 1 (0.005) with (GG), with a frequency of 0.04 (4%) for the polymorphic allele. The inference of haplotypes resulted in 312 (0.78) AA, 72 (0.18) GA, and 16 (0.04) GG haplotypes. The AG haplotype was not found. The variants were found to be in linkage disequilibrium (D' = 1). Of the nine possible diplotypes, AA/AG, AA/GG, and AG/GG were not found, in concordance with the hypothesis that the G allele of c.*96A>G does not occur in the absence of the G allele of c.1055A>G. We found a slight correlation between ASA biochemical activity and variants, mainly due to the G allele of c.*96A>G in either genotypes or haplotypes.
In Northwestern Mexico, the presence of PD-ASA alleles was biochemically and molecularly determined, and the frequencies were found to be in HWE. The frequency of PD-ASA for the North Western Mexican mestizo is 8%.
异染性脑白质营养不良（MLD，OMIM 250100）是一种神经退行性疾病，由 ARSA 基因（OMIM 607574）中的突变引起，导致芳基硫酸酯酶 A（ASA）缺乏。ASA 假缺陷（PD-ASA）是一种生化状况，极大地降低了 ASA 的活性，但与临床表现无关。PD-ASA 与 c.1055A>G（p.Asn352Ser）（rs2071421）和 c.*96A>G（rs6151429）变体相关，其在人群中的估计频率为 2%。
确定芳基硫酸酯酶 A 的活性，并鉴定墨西哥假缺陷个体中 ARSA 基因的变体和单倍型。
纳入了 200 名看似健康的个体，通过分光光度分析测定白细胞中 ASA 的酶活性，并通过 PCR-RFLP 分析鉴定 PD-ASA 等位基因。通过半自动 Sanger 测序确认基因型。使用 Arlequin v.10.04 构建单倍型，并使用 Cube X 进行连锁不平衡分析。
确定 ASA 的酶活性为 1.74-2.09 nmol/mg 蛋白/分钟，随后与基因型和单倍型相关。对于（p.Asn352Ser）变体，我们发现 126 名（0.63）个体具有 AA 基因型，62 名具有 AG（0.31）和 12 名具有 GG（0.06）；多态性等位基因的频率为 0.215（86 个等位基因，21.5%），且变体处于哈迪-温伯格平衡（p = 0.2484）。变体 c.*96A>G 也处于哈迪-温伯格平衡（p = 0.2105）：185 名（0.925）个体具有 AA 基因型，14 名（0.07）具有 AG，1 名（0.005）具有 GG，多态性等位基因的频率为 0.04（4%）。单倍型推断产生了 312 个（0.78）AA、72 个（0.18）GA 和 16 个（0.04）GG 单倍型。未发现 AG 单倍型。发现变体处于连锁不平衡（D'=1）状态。在九个可能的二倍型中，未发现 AA/AG、AA/GG 和 AG/GG，这与 c.*96A>G 的 G 等位基因不存在于 c.1055A>G 的 G 等位基因的假设一致。我们发现 ASA 生化活性与变体之间存在轻微相关性，主要归因于 c.*96A>G 中的 G 等位基因，无论是在基因型还是单倍型中。
在墨西哥西北部，通过生化和分子方法确定了 PD-ASA 等位基因的存在，且发现其频率处于哈迪-温伯格平衡状态。西北墨西哥混血儿的 PD-ASA 频率为 8%。
