Severe combined immunodeficiency (SCID) consists of a group of disorders defined by abnormal B and T cell development that typically results in death within the first year of life if undiagnosed or untreated. Reticular dysgenesis (RD) is a rare but especially severe form of SCID that is caused by adenylate kinase 2 deficiency and is characterized not only by lymphopenia but also by profound neutropenia. RD predisposes patients to viral and fungal infections typical of SCID as well as serious bacterial infections atypical in the neonatal period in other SCID types. RD is also associated with sensorineural hearing loss not typically seen in other forms of SCID. Without rapid diagnosis and curative hematopoietic stem cell transplantation, RD is fatal within days to months due to overwhelming bacterial infection. The inclusion of the T cell receptor excision circle assay nationally in 2017 on the newborn screen has facilitated diagnosis of SCID in the neonatal period. This case reports on a male infant with RD who presented after preterm birth with severe cytopenias and a gastrointestinal anomaly and ultimately developed severe bacterial sepsis. Postmortem bone marrow evaluation and panel-based gene sequencing identifying 2 novel variants in the adenylate kinase 2 gene provided confirmation for a diagnosis of RD. This case emphasizes the importance of thorough diagnostic evaluation, including the newborn screen, in neonates and infants with persistent and unexplained cytopenias. Prompt hematology and/or immunology referral is advised for disease management and to facilitate hematopoietic stem cell transplantation to optimize long-term survival.

中文翻译：

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网状发育不全：新生儿罕见的免疫缺陷，伴有血细胞减少和细菌性败血症。

严重联合免疫缺陷 (SCID) 是一组由 B 细胞和 T 细胞发育异常定义的疾病，如果未经诊断或不治疗，通常会导致出生后第一年内死亡。网状发育不全 (RD) 是一种罕见但特别严重的 SCID，由腺苷酸激酶 2 缺陷引起，其特征不仅是淋巴细胞减少，还包括严重的中性粒细胞减少。RD 使患者容易遭受 SCID 典型的病毒和真菌感染，以及其他 SCID 类型新生儿期非典型的严重细菌感染。RD 还与感音神经性听力损失有关，这在其他形式的 SCID 中并不常见。如果不进行快速诊断和治疗性造血干细胞移植，RD 会因大量细菌感染而在数天至数月内致命。2017年全国范围内将T细胞受体切除环检测纳入新生儿筛查，促进了新生儿期SCID的诊断。该病例报告了一名患有 RD 的男婴，他在早产后出现严重的血细胞减少和胃肠道异常，并最终发展为严重的细菌性败血症。尸检骨髓评估和基于组的基因测序鉴定出腺苷酸激酶 2 基因中的 2 个新变异，为 RD 的诊断提供了确认。该病例强调了对患有持续性不明原因血细胞减少症的新生儿和婴儿进行彻底诊断评估（包括新生儿筛查）的重要性。建议立即进行血液学和/或免疫学转诊以进行疾病管理并促进造血干细胞移植以优化长期生存。