Ambrosio Adelaide, Fioretti Tiziana, D'Andrea Barbara, Pezone Lucia, Bitetti Ilaria, Di Domenico Carmela, Vallone Sabrina, Maiolo Valeria, Cioce Angela, Giustino Mariano, Varone Antonio, Esposito Gabriella
CEINGE Advanced Biotechnologies Franco Salvatore, s.c.a r.l., 80145 Naples, Italy.
Neurology Unit, Santobono-Pausilipon Children Hospital, 80122 Naples, Italy.
Int J Neonatal Screen. 2025 Aug 17;11(3):64. doi: 10.3390/ijns11030064.
Three targeted therapies are currently available for spinal muscular atrophy (SMA), which have dramatically changed the natural history of this severe and potentially fatal disease. More than 95% of SMA cases have a homozygous deletion of exon 7 of the gene. Disease expression mainly depends on the copy number of , a hypomorphic copy of . Many countries in the world have implemented newborn screening (NBS) programs for early identification and treatment of children with SMA. We herein present the first two-year results of the SMA NBS program in Campania, a region with one of the highest birth rates in Italy. Genomic DNA was extracted from dried blood spots (DBS) and peripheral blood. For DBS, the gene copy number was evaluated by quantitative polymerase chain reaction (qPCR) targeting exon 7 and a reference gene (). In positive newborns and their parents, / copies were evaluated by multiplex ligation probe amplification (MLPA). We analyzed 77,945 newborns and identified 11 positive children. Six patients had 2 copies of , but only one showed severe SMA-related signs at birth. Eligible newborns were treated with gene therapy within 20 days of birth. Notably, qPCR failed to amplify the reference gene in 10/77,945 DBS. Despite this limitation, we observed that about 1/40 DBS had ΔCt values consistent with the presence of one copy. The semi-automated procedure used for SMA NBS showed excellent performance in detecting the presence of homozygous deletion of exon 7, with the exception of a few cases with the absence of amplification of the reference gene. By solving this limitation, the screening procedure has the potential to detect heterozygous carriers of the deletion and, consequently, identify families at procreative risk of SMA.
目前有三种靶向疗法可用于治疗脊髓性肌萎缩症（SMA），这极大地改变了这种严重且可能致命疾病的自然病程。超过95%的SMA病例存在该基因第7外显子的纯合缺失。疾病表现主要取决于存活运动神经元1（SMN1）的拷贝数，而SMN2是SMN1的一个功能减退拷贝。世界上许多国家已实施新生儿筛查（NBS）项目，用于早期识别和治疗SMA患儿。我们在此展示了坎帕尼亚地区SMA NBS项目的首个两年结果，该地区是意大利出生率最高的地区之一。从干血斑（DBS）和外周血中提取基因组DNA。对于DBS，通过靶向第7外显子和一个参考基因（RPP30）的定量聚合酶链反应（qPCR）评估SMN1基因拷贝数。在阳性新生儿及其父母中，通过多重连接探针扩增（MLPA）评估SMN1/SMN2拷贝数。我们分析了77945名新生儿，确定了11名阳性儿童。6名患者有2个SMN2拷贝，但只有1名在出生时表现出严重的SMA相关体征。符合条件的新生儿在出生后20天内接受了基因治疗。值得注意的是，在77945份DBS样本中，有10份qPCR未能扩增出参考基因RPP30。尽管存在这一局限性，但我们观察到约1/40的DBS样本ΔCt值与存在1个SMN2拷贝一致。用于SMA NBS的半自动程序在检测SMN1第7外显子纯合缺失的存在方面表现出色，除了少数参考基因未扩增的情况。通过解决这一局限性，筛查程序有可能检测到SMN1缺失的杂合携带者，从而识别出有SMA生育风险的家庭。
