Omenn syndrome (OS) is a type of severe combined immunodeficiency (SCID) that is distinguished by, lymphadenopathy, hepatosplenomegaly, erythroderma, alopecia with normal to elevated T-cell counts, eosinophilia, and elevated serum IgE levels. Recombination activation gene (RAG) 1 or RAG2 mutations that result in partial V(D)J recombination activity are known to be the main cause of OS. Other genes (DCLRE1C, LIG4, IL7RA, common gamma chain, ADA, RMRP, and CHD7) have also been linked to OS, although with low frequency. Here, we report a two-month-old Moroccan girl from consanguineous marriage with chronic diarrhea, recurrent and opportunistic infections, failure to thrive, desquamative erythroderma, hepatosplenomegaly, and axillary lymphadenitis. The immunological assessment showed normal lymphocyte and NK cell counts but an absence of B cells, agammaglobulinemia contrasting with a high level of IgE. On the other hand, Sanger sequencing of RAG1 and RAG2 exon 2 regions revealed a new homozygous deleterious mutation in the RAG1 gene. This c.1184C > T mutation caused a change from Proline to Leucine at position 395 of the protein, leading to a partial loss of function. Early and rapid diagnosis of the disease may facilitate urgent life-saving treatment.

Omenn 综合征 (OS) 是一种严重的联合免疫缺陷 (SCID)，其特点是淋巴结病、肝脾肿大、红皮病、脱发伴 T 细胞计数正常至升高、嗜酸性粒细胞增多和血清 IgE 水平升高。已知导致部分 V(D)J 重组活性的重组激活基因 (RAG) 1 或 RAG2 突变是 OS 的主要原因。其他基因（DCLRE1C、LIG4、IL7RA、常见 γ 链、ADA、RMRP 和 CHD7）也与 OS 相关，尽管频率较低。在这里，我们报告了一名来自近亲结婚的两个月大的摩洛哥女孩，她患有慢性腹泻、复发性和机会性感染、发育迟缓、脱屑性红皮病、肝脾肿大和腋窝淋巴结炎。免疫学评估显示淋巴细胞和 NK 细胞计数正常，但没有 B 细胞，与高水平 IgE 形成对比的无丙种球蛋白血症。另一方面，RAG1 和 RAG2 外显子 2 区域的 Sanger 测序揭示了 RAG1 基因中新的纯合有害突变。这种 c.1184C > T 突变导致蛋白质的 395 位从脯氨酸变为亮氨酸，导致部分功能丧失。该疾病的早期和快速诊断可能有助于紧急挽救生命的治疗。