Kingma H A, van der Sluijs F H, Heiner-Fokkema M R
Laboratory of Metabolic Diseases, Department of Laboratory Medicine, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
Ann Clin Biochem. 2018 Nov;55(6):693-701. doi: 10.1177/0004563218779609. Epub 2018 Jun 11.
Background Congenital disorders of glycosylation (CDG) are a growing group of rare genetic disorders. The most frequently used screening method is sialotransferrin profiling using isoelectric focusing (IEF). Capillary zone electrophoresis (CZE) may be a simple and fast alternative. We investigated the Capillarys™ CDT assay (Sebia, France) to screen for N-glycosylation disorders, using IEF as gold standard. Methods Intra- and inter-assay precision were established, and analyses in heparin-anticoagulated plasma and serum were compared. Accuracy was assessed by comparing IEF and CZE profiles of 153 samples, including 49 normal, 53 CDG type I, 2 CDG type II, 1 combined CDG type I and type II and 48 samples with a Tf-polymorphism. Neuraminidase-treated plasma was analysed to discriminate CDG and Tf-polymorphisms using samples of 52 subjects (25 had a confirmed Tf-polymorphism). Age-dependent reference values were established using profiles of 312 samples. Results Heparin-plasma is as suitable as serum for CDG screening with the Capillarys™ CDT assay. The precision of the method is high, with a limit of quantification (LOQ) of 0.5%. All profiles, including CDG and Tf-polymorphisms, were correctly identified with CZE. Forty-nine of 52 neuraminidase-treated samples correctly identified the presence/absence of a Tf-polymorphism. Interferences in 3/52 samples hampered interpretation. Sialo-Tf profiles were dependent of age, in particular in the first three months of age. Conclusions CZE analysis with the Capillarys™ CDT kit (Sebia) is a fast and reliable method for screening of N-glycosylation defects. Tf-polymorphisms could be excluded after overnight incubation with neuraminidase.
糖基化先天性疾病（CDG）是一类日益增多的罕见遗传疾病。最常用的筛查方法是使用等电聚焦（IEF）进行唾液酸转铁蛋白分析。毛细管区带电泳（CZE）可能是一种简单快速的替代方法。我们以IEF作为金标准，研究了Capillarys™ CDT检测法（法国赛比公司）用于筛查N-糖基化疾病。方法：确定了批内和批间精密度，并比较了肝素抗凝血浆和血清的分析结果。通过比较153份样本的IEF和CZE图谱评估准确性，其中包括49份正常样本、53份I型CDG样本、2份II型CDG样本、1份I型和II型联合CDG样本以及48份具有转铁蛋白多态性的样本。使用52名受试者的样本（25名已确认有转铁蛋白多态性）分析神经氨酸酶处理后的血浆，以区分CDG和转铁蛋白多态性。使用312份样本的图谱建立年龄相关参考值。结果：使用Capillarys™ CDT检测法进行CDG筛查时，肝素血浆与血清一样适用。该方法精密度高，定量限（LOQ）为0.5%。所有图谱，包括CDG和转铁蛋白多态性，均通过CZE正确识别。52份神经氨酸酶处理样本中有49份正确识别了转铁蛋白多态性的存在与否。52份样本中有3份的干扰妨碍了解读。唾液酸转铁蛋白图谱与年龄有关，尤其是在出生后的前三个月。结论：使用Capillarys™ CDT试剂盒（赛比公司）进行CZE分析是一种快速可靠的N-糖基化缺陷筛查方法。与神经氨酸酶过夜孵育后可排除转铁蛋白多态性。
