Zhang Ying, Chen Juan, Feng Zonghui, Li Wencheng
Reproductive Medicine Center, Renmin Hospital, Hubei University of Medicine, Shiyan, Hubei, People's Republic of China.
Prenatal Diagnosis Center, Renmin Hospital, Hubei University of Medicine, Shiyan, Hubei, People's Republic of China.
Mol Cytogenet. 2022 Aug 15;15(1):34. doi: 10.1186/s13039-022-00614-0.
Unbalanced chromosome abnormalities (UBCA) are either gains or losses or large genomic regions, but the affected person is not or only minimally clinically affected. Copy number variants (CNVs) are an important source of normal and pathogenic genome variations. CNVs and UBCA identified in prenatal cases need careful considerations and correct interpretation if those are harmless or harmful variants from the norm.
A 25-year-old, gravida 1, para 0, woman underwent amniocentesis at 18 weeks of gestation because the noninvasive prenatal testing (NIPT) results revealed a 6.8 Mb duplication from 2q11.1 to 2q11.2. Chromosomal microarray analysis (CMA) was performed on uncultured amniocytes. GTG-banding karyotype analysis on cultured amniocytes was performed.
Chromosomal GTG-banding of the cultured amniocytes revealed a karyotype of 46,XX. CMA detected a 6.8-Mb chromosomal duplication in the region of 2q11.1q11.2 (arr[GRCh37] 2q11.1q11.2(95,327,873_102,088,148)x3).
Chromosomal microdeletions and microduplications are difficult to detect by conventional cytogenetics, combination of prenatal ultrasound, karyotype analysis, NIPT, CMA and genetic counseling is helpful for the prenatal diagnosis of UBCA and chromosomal microdeletions/microduplications.
染色体不平衡异常（UBCA）表现为基因组大片段的获得或缺失，但受影响个体在临床上无明显表现或仅有轻微影响。拷贝数变异（CNV）是正常和致病基因组变异的重要来源。产前病例中鉴定出的CNV和UBCA，若为无害或有害变异，需仔细考虑并正确解读。
一名25岁初产妇，孕1产0，孕18周时因无创产前检测（NIPT）结果显示2q11.1至2q11.2存在6.8Mb重复而接受羊水穿刺。对未培养的羊水细胞进行了染色体微阵列分析（CMA），并对培养的羊水细胞进行了GTG带核型分析。
培养的羊水细胞染色体GTG带分析显示核型为46,XX。CMA检测到2q11.1q11.2区域存在6.8Mb染色体重复（arr[GRCh37] 2q11.1q11.2(95,327,873_102,088,148)x3）。
传统细胞遗传学难以检测染色体微缺失和微重复，产前超声、核型分析、NIPT、CMA和遗传咨询相结合有助于UBCA及染色体微缺失/微重复的产前诊断。
