探讨海南省新生儿希特林蛋白缺乏症(CD)发病率及基因突变特点。

选择2024年2至11月出生在海南省各助产、医疗机构的74 916例新生儿足跟血干血斑样本为研究对象。采用串联质谱(MS/MS)法，对CD筛查的指标干血斑中瓜氨酸浓度进行检测。对2024年2至4月出生新生儿，先采用NeoBase™ 2试剂盒设定的干血斑检测瓜氨酸浓度≥28.99 μmol/L作为初筛新生儿被召回复筛的初始切值上限；再采用百分位数法，对瓜氨酸浓度数据计算本研究初筛新生儿被召回复筛的瓜氨酸浓度新切值上限(≥27.00 μmol/L)，最终以该切值上限作为本研究筛查疑似CD患儿的依据。对纳入本研究新生儿足跟血干血斑初筛与复筛结果均为瓜氨酸浓度≥27.00 μmol/L的疑似CD患儿，均采用全外显子组测序(WES)检测基因突变情况。本研究经海南省妇女儿童医学中心医学伦理委员会批准[审批文号：HNWCMC伦审2024年第(55)号]。所有受试儿监护人签署遗传代谢病免费筛查知情同意书。

本研究共计筛查74 916例2024年2至11月出生的新生儿足跟血干血斑样本。根据对2024年2至4月筛查的29 676例新生儿干血斑样本瓜氨酸浓度筛查结果，计算本研究CD筛查新生儿的瓜氨酸浓度正常参考值为4.90~27.00 μmol/L。本研究共确诊CD患儿为5例，包括2例漏筛，后因黄疸住本院而被确诊者，以及SLC25A13基因突变携带者2例，确诊者为SLC25A13基因发生2个位点疑似致病性或致病性(LP/P)突变，携带者仅1个位点LP/P突变；海南省2024年2至11月新生儿CD发病率为6.7×10^－5(5/74 916)。本研究检出SLC25A13基因c.852_855del、c.1751-5_1751-4ins和c.615＋5G>A共3种位点突变，其中c.852_855del为本研究检出的热点突变。

海南省新生儿CD发病率较高，SLC25A13基因突变以c.852_855del最常见。在新生儿CD筛查中，制定本地区瓜氨酸浓度正常参考范围，可以减少CD患儿漏筛。

To investigate the incidence and gene mutation characteristics of neonatal Citrin deficiency (CD) in Hainan Province.

A total of 74 916 dried blood spot samples collected from neonatal heel pricks were enrolled as research subjects, which were obtained from newborns delivered from February to November, 2024 in all midwifery and medical institutions across Hainan Province. Tandem mass spectrometry (MS/MS) was used to detect the concentration of citrulline in dried blood spots, an index of CD screening. For newborns born from February to April, citrulline concentration ≥ 28.99 μmol/L was taken as the upper limit of initial cut-off value of initial screening newborn being called back for re-screening, which was established based on the NeoBase™ 2 kit. A upper limit of new cut-off value (initial screening newborn with citrulline concentration ≥27.00 μmol/L were recalled for re-screening) was further calculated via the percentile method using the corresponding concentration data, and this new value served as the criterion for identifying suspected CD cases in this research. For suspected CD infants whose neonatal heel prick dried blood spot samples showed citrulline concentration ≥27.00 μmol/L in both initial screening and re-screening from February to November 2024, whole-exome sequencing (WES) was performed to detect gene mutations. This study obtained approval from the Medical Ethics Committee of Hainan Women and Children′s Medical Center (Approval No. HNWCMC Ethics Review 2024-55), and informed consent forms for free inherited metabolic disease screening were signed by the guardians of all enrolled infants.

A total of 74 916 neonatal heel prick dried blood spot samples underwent screening from February to November 2024. The new citrulline concentration normal reference value for neonatal CD screening was 4.90-27.00 μmol/L, which was calculated using data of screening results of citrulline concentration from 29 676 samples collected from February to April. Five CD cases were confirmed, including 2 missed cases diagnosed post-admission for jaundice, and 2 SLC25A13 gene mutation carriers were detected. The CD patients carried two suspected pathogenicity or pathogenicity (LP/P) mutations in the SLC25A13 gene, whereas the carriers had only one such mutation. The CD incidence rate of newborns in Hainan province during February to November in 2024 was 6.7×10^-5 (5/74 916). Three SLC25A13 gene mutations (c.852_855del, c. 1751-5_1751-4ins, c. 615+ 5G>A) were detected, with c. 852_855del being the hot-spot mutation in this study.

The study revealed a relatively high incidence of CD among newborns in Hainan province, with c. 852_855del being the most prevalent SLC25A13 gene mutation. Establishing a local normal reference range for citrulline concentration in neonatal CD screening can reduce the rate of missed diagnosis of CD infants.