McLean-Tooke A, Spickett G P, Gennery A R
Department of Immunology, Royal Victoria InfirmaryDepartment of Paediatric Immunology, Newcastle General Hospital, Newcastle-Upon-Tyne, UK.
Scand J Immunol. 2007 Jul;66(1):1-7. doi: 10.1111/j.1365-3083.2007.01949.x.
22q11.2 deletion syndrome is the commonest chromosome deletion syndrome. 22q11.2 deletion may result in variable clinical phenotypes which may differ even between patients with identical deletions. Abnormal pharyngeal arch development results in defects in the development of the parathyroid glands, thymus and conotruncal region of the heart. Defective thymic development is associated with impaired immune function. 'Complete' DiGeorge syndrome with total absence of the thymus and a severe T-cell immunodeficiency accounts for <0.5% of patients. The majority of patients with 22q11.2 deletion syndromes have 'partial' defects with impaired thymic development rather than complete absence with variable defects in T-cell numbers. Immunodeficiency in these patients is not solely due to T-cell deficiency and abnormalities of T-cell clonality or impairment of proliferative responses may play a role. Humoral deficiencies including defects in the B-cell compartment have also been identified in these patients. 22q11.2 deletion syndrome patients are at increased risk of a variety of autoimmune diseases. A number of immune defects may predispose to the development of autoimmunity in these patients including increased infection, impaired development of natural T-regulatory cells and impaired thymic central tolerance.
22q11.2 缺失综合征是最常见的染色体缺失综合征。22q11.2 缺失可能导致多种临床表型，即使是具有相同缺失的患者之间也可能有所不同。咽弓发育异常会导致甲状旁腺、胸腺和心脏圆锥干区域发育缺陷。胸腺发育不良与免疫功能受损有关。胸腺完全缺失且伴有严重 T 细胞免疫缺陷的“完全型”迪乔治综合征患者占比不到 0.5%。大多数 22q11.2 缺失综合征患者存在胸腺发育不良的“部分型”缺陷，而非完全缺失，T 细胞数量存在不同程度的缺陷。这些患者的免疫缺陷并非仅由 T 细胞缺乏所致，T 细胞克隆性异常或增殖反应受损可能也起了作用。在这些患者中还发现了包括 B 细胞区室缺陷在内的体液免疫缺陷。22q11.2 缺失综合征患者患多种自身免疫性疾病的风险增加。多种免疫缺陷可能使这些患者易患自身免疫性疾病，包括感染增加、天然 T 调节细胞发育受损以及胸腺中枢耐受受损。
