Nourizadeh Maryam, Shakerian Leila, Borte Stephan, Fazlollahi Mohammadreza, Badalzadeh Mohsen, Houshmand Massoud, Alizadeh Zahra, Dalili Hossein, Rashidi-Nezhad Ali, Kazemnejad Anoshirvan, Moin Mostafa, Hammarström Lennart, Pourpak Zahra
Immunology, Asthma and Allergy Research Institute, Tehran University of Medical Sciences, Tehran, Iran.
ImmunoDeficiencyCenter Leipzig (IDCL), Jeffrey Modell Diagnostic and Research Center for Primary Immunodeficiencies, Municipal Hospital, Leipzig, Germany.
Scand J Immunol. 2018 Aug;88(2):e12699. doi: 10.1111/sji.12699.
T-cell receptor excision circles (TRECs) and κ-deleting recombination excision circles (KRECs) are recently used for detection of T or B cell lymphopenia in neonates based on region-specific cutoff levels. Here, we report cutoffs for TREC and KREC copies useful for newborn screening and/or diagnosis of primary immunodeficiency diseases (PID) in Iran. DNA was extracted from a single 3.2 mm punch of dried blood spots collected from 2160 anonymized newborns referred to two major referral health centres between 2014 and 2016. For refinement of the cutoffs, 51 patients with a definite diagnosis of severe combined immunodeficiency, X-linked agammaglobulinaemia and combined immunodeficiency, including ataxia telangiectasia, human phosphoglucomutase 3 and Janus kinase-3 deficiency, as well as 47 healthy controls were included. Samples from patients with an X-linked hyper-IgM-syndrome, Wiskott-Aldrich syndrome and DNA ligase 4 deficiency were considered as disease controls. Triplex-quantitative real-time PCR was used. Cutoffs were calculated as TRECs < 11 and KRECs < 6 copies with an ACTB > 700 copies with sensitivity of 100% for TREC and 97% for KREC. Among thirty anonymized newborn samples (1.5%) with abnormal results for TREC and/or KREC, only twenty-one available cases were retested and shown to be in the normal range except for three samples (0.15%). All of the patients with a definitive diagnosis were correctly identified based on our established TREC/KREC copy numbers. Determining cutoffs for TREC/KREC is essential for correctly identifying children with PID in newborn screening. Early diagnosis of PID patients enables appropriate measures and therapies like stem cell transplantation.
T细胞受体切除环（TRECs）和κ-缺失重组切除环（KRECs）最近被用于根据区域特异性临界水平检测新生儿的T或B细胞淋巴细胞减少症。在此，我们报告了在伊朗可用于新生儿筛查和/或原发性免疫缺陷疾病（PID）诊断的TREC和KREC拷贝数临界值。从2014年至2016年转诊至两个主要转诊健康中心的2160名匿名新生儿采集的干血斑中，取单个3.2毫米打孔样本提取DNA。为了优化临界值，纳入了51例确诊为严重联合免疫缺陷、X连锁无丙种球蛋白血症和联合免疫缺陷的患者，包括共济失调毛细血管扩张症、人磷酸葡萄糖变位酶3和Janus激酶-3缺乏症患者，以及47名健康对照。来自X连锁高IgM综合征、威斯科特-奥尔德里奇综合征和DNA连接酶4缺乏症患者的样本被视为疾病对照。采用三重定量实时PCR。计算得出的临界值为TRECs < 11拷贝、KRECs < 6拷贝，且β-肌动蛋白（ACTB）> 700拷贝，TREC的灵敏度为100%，KREC的灵敏度为97%。在30份TREC和/或KREC结果异常的匿名新生儿样本（1.5%）中，仅对21份可用病例进行了复测，除3份样本（0.15%）外，其余均显示在正常范围内。根据我们确定的TREC/KREC拷贝数，所有确诊患者均被正确识别。确定TREC/KREC的临界值对于在新生儿筛查中正确识别PID患儿至关重要。PID患者的早期诊断能够采取适当措施和治疗，如干细胞移植。
