Gene identification in the congenital disorders of glycosylation type I by whole-exome sequencing
Gene identification in the congenital disorders of glycosylation type I by whole-exome sequencing
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DOI：
10.1093/hmg/dds123
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发表时间：
2012-10-01
影响因子：
3.5
通讯作者：
Lefeber, Dirk J.
中科院分区：
文献类型：
--
作者：
Timal, Sharita;Hoischen, Alexander;Lefeber, Dirk J.
先天性糖基化I型（CDG-I）疾病是一组不断增长的隐性神经代谢疾病。疾病基因的鉴定受到临床症状的巨大异质性和涉及的大量潜在基因的影响。到目前为止，基因鉴定包括在血液样品和成纤维细胞中连续应用生物化学方法。在遗传学未解决的情况下，纯合性定位已被应用于近亲家庭。总而言之，这种耗时的诊断策略导致在17个不同的CDG-I基因中鉴定出缺陷。在这里，我们将全外显子组测序（WES）与蛋白质N-糖基化途径的知识相结合，用于我们剩余的6名来自无关非血缘家庭的未解决的CDG-I患者的基因鉴定。基于76个潜在的CDG-I候选基因的列表对外显子组变体进行优先排序，从而快速鉴定一个已知的和两个新的CDG-I基因缺陷。这些包括由于ALG 13中的从头突变而导致的第一个X-连锁的CDG-I，以及DPAGT 1中的复合杂合突变，以及多萜醇-PP-聚糖组装中的前两个步骤，以及在两种情况下涉及核苷酸糖生物合成的PGM 1中的突变。通过显示患者成纤维细胞中相应酶的活性缺陷来证实突变的致病性。结合这些结果，在我们的CDG-I患者中，98%的患者都发现了基因缺陷。我们的研究结果暗示了WES在新诊断的单胎家庭中解开CDG-I中疾病基因的潜力。
Congenital disorders of glycosylation type I (CDG-I) form a growing group of recessive neurometabolic diseases. Identification of disease genes is compromised by the enormous heterogeneity in clinical symptoms and the large number of potential genes involved. Until now, gene identification included the sequential application of biochemical methods in blood samples and fibroblasts. In genetically unsolved cases, homozygosity mapping has been applied in consanguineous families. Altogether, this time-consuming diagnostic strategy led to the identification of defects in 17 different CDG-I genes. Here, we applied whole-exome sequencing (WES) in combination with the knowledge of the protein N-glycosylation pathway for gene identification in our remaining group of six unsolved CDG-I patients from unrelated non-consanguineous families. Exome variants were prioritized based on a list of 76 potential CDG-I candidate genes, leading to the rapid identification of one known and two novel CDG-I gene defects. These included the first X-linked CDG-I due to a de novo mutation in ALG13, and compound heterozygous mutations in DPAGT1, together the first two steps in dolichol-PP-glycan assembly, and mutations in PGM1 in two cases, involved in nucleotide sugar biosynthesis. The pathogenicity of the mutations was confirmed by showing the deficient activity of the corresponding enzymes in patient fibroblasts. Combined with these results, the gene defect has been identified in 98% of our CDG-I patients. Our results implicate the potential of WES to unravel disease genes in the CDG-I in newly diagnosed singleton families.