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Abstract：
Monosomy 7 is generally considered as an acquired cytogenetic abnormality within hematopoietic cells, and indicates an especially high risk of progression to bone marrow failure, myelodysplastic syndrome (MDS) or juvenile myelomonocytic leukemia (JMML). We report a case of a 6-month-old female infant with mosaic monosomy 7 who presented with clinical and laboratory evidences of immunodeficiency. The patient had suffered from recurrent respiratory infections since she was born. Peripheral blood lymphocyte subsets revealed an extremely low level of CD19+ B lymphocytes (0.3∼0.8%, normal range: 6.4∼22.6%) and a decreased CD4/CD8 ratio (0.67∼1.12, normal range: 1.4∼2.0). Decreased serum levels of IgG (1.53 g/L, normal range: 4.09∼7.03 g/L), IgA (0.10 g/L, normal range: 0.21∼0.47 g/L) and IgM (0.26 g/L, normal range: 0.33∼0.73 g/L) were detected, while complements were normal. Excepting transient neutropenia, routine blood tests were within normal limits. Clinical exome sequencing identified a de novo mosaic monosomy 7, while no pathogenic mutation associated with immunodeficiency was detected. However, peripheral blood cytogenetic analysis was failure to detect monosomy 7 due to the very few cell mitosis. Subsequent fluorescence in situ hybridization (FISH) identified a mosaic monosomy 7 in 58 cells within a total number of 100 cells, which was consistent with clinical exome sequencing. Therefore, the patient was diagnosed with primary immunodeficiency disease (PID) due to mosaic monosomy 7. Intravenous treatment with multiple antibiotic agents and infusion of gamma globulin could control the patient\'s respiratory infections effectively. A better understanding of PIDs will enable effective treatments and prevention of infections in these patients.
摘要：
单体7通常被认为是造血细胞内的获得性细胞遗传学异常，并表明进展为骨髓衰竭的风险特别高，骨髓增生异常综合征（MDS）或幼年型粒单核细胞白血病（JMML）。我们报告了一例6个月大的女性婴儿，患有7号马赛克单体，并具有免疫缺陷的临床和实验室证据。该患者自出生以来患有反复呼吸道感染。外周血淋巴细胞亚群显示CD19+B淋巴细胞水平极低(0.3~0.8%，正常范围：6.4~22.6%）和CD4/CD8比值降低（0.67~1.12，正常范围：1.4~2.0）。血清IgG水平降低（1.53g/L，正常范围：4.09〜7.03g/L），IgA（0.10g/L，正常范围：0.21~0.47g/L)和IgM(0.26g/L，正常范围：0.33~0.73g/L)检测到，而补充是正常的。除了一过性中性粒细胞减少症,血常规检查在正常范围内.临床外显子组测序鉴定了从头镶嵌单体7,而未检测到与免疫缺陷相关的致病突变。然而,由于很少的细胞有丝分裂，外周血细胞遗传学分析未能检测到单体7。随后的荧光原位杂交（FISH）在总共100个细胞中的58个细胞中鉴定出镶嵌单体7，这与临床外显子组测序一致。因此,患者被诊断为原发性免疫缺陷疾病（PID），由于马赛克7。静脉应用多种抗生素及输注丙种球蛋白可有效控制患者呼吸道感染。更好地了解PID将能够有效治疗和预防这些患者的感染。
