Severe combined immunodeficiency (SCID) is a heterogeneous group of primary immunodeficiency diseases (PIDs) characterized by a lack of autologous T lymphocytes. This severe PID is rare, but has a higher prevalence in populations with high rates of consanguinity. The epidemiological, clinical, and immunological features of SCIDs in Moroccan patients have never been reported. The aim of this study was to provide a clinical and immunological description of SCID in Morocco and to assess changes in the care of SCID patients over time. This cross-sectional retrospective study included 96 Moroccan patients referred to the national PID reference center at Casablanca Children’s Hospital for SCID over two decades, from 1998 to 2019. The case definition for this study was age < 2 years, with a clinical phenotype suggestive of SCID, and lymphopenia, with very low numbers of autologous T cells, according to the IUIS Inborn Errors of Immunity classification. Our sample included 50 male patients, and 66% of the patients were born to consanguineous parents. The median age at onset and diagnosis were 3.3 and 6.5 months, respectively. The clinical manifestations commonly observed in these patients were recurrent respiratory tract infection (82%), chronic diarrhea (69%), oral candidiasis (61%), and failure to thrive (65%). The distribution of SCID phenotypes was as follows: T−B−NK+ in 44.5%, T−B−NK− in 32%, T−B+NK− in 18.5%, and T−B+NK+ in 5%. An Omenn syndrome phenotype was observed in 15 patients. SCID was fatal in 84% in the patients in our cohort, due to the difficulties involved in obtaining urgent access to hematopoietic stem cell transplantation, which, nevertheless, saved 16% of the patients. The autosomal recessive forms of the clinical and immunological phenotypes of SCID, including the T−B−NK+ phenotype in particular, were more frequent than those in Western countries. A marked improvement in the early detection of SCID cases over the last decade was noted. Despite recent progress in SCID diagnosis, additional efforts are required, for genetic confirmation and particularly for HSCT.

严重联合免疫缺陷 (SCID) 是一组异质性原发性免疫缺陷疾病 (PID)，其特征是缺乏自体 T 淋巴细胞。这种严重的 PID 很少见，但在血缘关系高的人群中患病率较高。从未报道过摩洛哥患者 SCID 的流行病学、临床和免疫学特征。本研究的目的是提供摩洛哥 SCID 的临床和免疫学描述，并评估 SCID 患者护理随时间的变化。这项横断面回顾性研究包括 1998 年至 2019 年 20 年间因 SCID 转诊至卡萨布兰卡儿童医院国家 PID 参考中心的 96 名摩洛哥患者。本研究的病例定义为年龄 < 2 岁，临床表型提示SCID和淋巴细胞减少症，根据IUIS先天免疫错误分类，自体T细胞数量非常少。我们的样本包括 50 名男性患者，其中 66% 的患者是近亲父母所生。发病和诊断的中位年龄分别为 3.3 个月和 6.5 个月。这些患者常见的临床表现是反复呼吸道感染（82%）、慢性腹泻（69%）、口腔念珠菌病（61%）和发育迟缓（65%）。SCID 表型的分布如下：44.5% 为 T-B-NK+，32% 为 T-B-NK-，18.5% 为 T-B+NK-，5% 为 T-B+NK+。在 15 名患者中观察到 Omenn 综合征表型。由于难以获得紧急造血干细胞移植，在我们队列中的患者中有 84% 的 SCID 是致命的，尽管如此，挽救了16%的患者。SCID 临床和免疫表型的常染色体隐性遗传形式，尤其是 T-B-NK+ 表型，比西方国家更常见。注意到在过去十年中早期发现 SCID 病例的显着改善。尽管最近在 SCID 诊断方面取得了进展，但仍需要额外的努力来进行基因确认，尤其是 HSCT。