部分性DiGeorge异常三例临床特征及分子诊断

Clinical features and molecular diagnosis of three patients with DiGeorge anomaly

目的探讨3例部分性DiGeorge异常患儿的临床特征和分子诊断方法。方法分析3例患儿的临床表现和免疫学特征，采用荧光原位杂交（FISH）方法检测染色体22q11．2基因缺失。结果（1）临床特征：3例患儿均有不同程度的感染病史和先天性心脏病，影像学检查提示胸腺小；2例患儿有明显的低钙血症（分别为1．11mmol／L和1．22mmol／L），并伴有惊厥；仅有1例有腭裂，均无明显的面部畸形。（2）免疫学特征：3例患儿均有不同程度的T细胞免疫功能缺陷（T淋巴细胞比例24％～43％，绝对值309～803个／μl），免疫球蛋白G、A、M水平，B淋巴细胞比例和绝对值均正常。（3）染色体22q11．2基因缺失检测：3例患儿各观察400个细胞，均显示2绿1红的杂交信号，表明存在染色体22q11．2的基因缺失。（4）预后：3例患儿均接受胸腺肽治疗，针对心脏畸形、低钙血症的临床干预，随访4—18个月，均预后良好。结论部分性DiGeorge异常临床表现多样，对于有先天性心脏病、胸腺小、低钙血症和免疫功能受损的患儿应考虑本病可能。采用FISH方法检测染色体22q11．2基因缺失，可作为准确、快速的诊断手段。胸腺肽治疗结合其他临床干预可能有效改善部分性DiGeorge异常的预后。

Objective To investigate the clinical features and molecular diagnostic methods of three patients with DiGeorge anomaly. Method The clinical manifestations and immunological features of the three cases with DiGeorge anomaly were analyzed. We detected the chromosome 22q11.2 gene deletion by fluorescence in situ hybridization （FISH）. Result （ 1 ） Clinical manifestations ： All three cases had varying degrees of infection, congenital heart disease and small thymus by imaging; two cases had significant hypocalcemia （1.11 mmoL/L and 1.22 retool/L, respectively）, accompanied by convulsions; only 1 case had cleft palate and all had no significant facial deformity. （2） Immunological characteristics： All three cases had varying degrees of T-cell immune function defects （percentage of T lymphoeytes was 24% -43% , absolute count was 309 -803/μ1）, and levels of immnnoglobnlin G, A, M, and percent of B lymphocytes and absolute count were normal. （3） Detection of the chromosome 22ql 1.2 gene deletion： 400 cells of each case were detected. All cells showed two green and one red hybridization signal, indicating the presence of gene deletions in chromosome 22q11.2. （4） Outcome： All three cases were treated with thymosin, and appropriate clinical intervention for cardiac malformations, hypocalcemia, and were followed-up for 4 - 18 months, the prognosis was good. Conclusion DiGeorge anomaly showed diverse clinical manifestations. We should consider the disease if patients had congenital heart disease, thymic hypoplasia, hypocalcemia and/or impaired immune function. FISH for detecting chromosome 22q11.2 gene deletion can be used as accurate and rapid diagnostic method. Thymosin treatment and other clinical intervention may help toimprove the prognosis of patients with partial DiGeorge anomaly.