Newborn Screening, Biochemistry and Pharmacology Laboratories, Clinic of Pediatric Neurology, Meyer University Children's Hospital, Florence, Italy; Department of Neurosciences, Psychology, Pharmacology and Child Health, University of Florence, Italy.
J Pharm Biomed Anal. 2014 Jan;88:201-6. doi: 10.1016/j.jpba.2013.08.044. Epub 2013 Sep 8.
Severe combined immunodeficiency due to adenosine-deaminase defect (ADA-SCID) is usually deadly in childhood because of severe recurrent infections. When clinical diagnosis is done, permanent damages due to infections or metabolite accumulation are often present. Gene therapy, bone marrow transplantation or enzyme replacement therapy may be effective if started early. The aim of this study was to set-up a robust method suitable for screening with a minimized preparation process and with inexpensive running costs, for diagnosing ADA-SCID by tandem mass spectrometry. ADA-SCID satisfies all the criteria for inclusion in a newborn screening program. We describe a protocol revised to incorporate adenosine and 2-deoxyadenosine testing into an expanded newborn screening program. We assessed the effectiveness of this approach testing dried blood spots from 4 genetically confirmed early-onset and 5 delayed-onset ADA-SCID patients. Reference values were established on 50,000 healthy newborns (deoxyadenosine <0.09μmol/L, adenosine <1.61μmol/L). We also developed a second tier test to distinguish true positives from false positives and improve the positive predictive value of an initial abnormal result. In the first 18 months, the pilot project has identified a newborn with a genetically confirmed defect in adenosine deaminase (ADA) gene. The results show that the method having great simplicity, low cost and low process preparations can be fully applicable to a mass screening program.
由于腺苷脱氨酶缺陷导致的严重联合免疫缺陷（ADA-SCID）在儿童时期通常是致命的，因为会发生严重的反复感染。当进行临床诊断时，由于感染或代谢物积累导致的永久性损害通常已经存在。如果早期开始，基因治疗、骨髓移植或酶替代疗法可能是有效的。本研究的目的是建立一种可靠的方法，通过最小化制备过程和降低运行成本，用于通过串联质谱法诊断 ADA-SCID。ADA-SCID 满足所有纳入新生儿筛查计划的标准。我们描述了一种经过修订的方案，将腺苷和 2-脱氧腺苷检测纳入扩展的新生儿筛查计划。我们评估了该方法在 4 例经基因证实的早发型和 5 例迟发型 ADA-SCID 患者的干血斑中的有效性。参考值是在 50000 名健康新生儿中建立的（脱氧腺苷 <0.09μmol/L，腺苷 <1.61μmol/L）。我们还开发了二级测试，以区分真正的阳性和假阳性，并提高初始异常结果的阳性预测值。在最初的 18 个月里，该试点项目已经发现了一名新生儿存在腺苷脱氨酶（ADA）基因缺陷。结果表明，该方法具有极大的简单性、低成本和低处理准备，可以完全适用于大规模筛查计划。
