一个13q大片段缺失家系的产前诊断及遗传咨询

Prenatal diagnosis and genetic counselling for a pedigree carrying a large fragment deletion of 13q

目的对1个孕20+周超声表现正常而无创产前检测提示为13q拷贝数异常的胎儿进行产前诊断。方法对胎儿羊水样本进行染色体核型分析和基因组拷贝数变异(copy number variation,CNV)检测;同时对胎儿父母行外周血染色体检查,以追溯胎儿染色体变异的来源。结果基因组CNV检测提示胎儿携带13q21.1q21.32区10.14 Mb的杂合缺失,该缺失来源于表型正常的母亲。胎儿及其父母的染色体核型均未见明显异常。结论携带13q21.1q21.32区10.14 Mb杂合缺失的胎儿及其母亲均无明显的异常,结合文献复习认为该片段缺失为良性变异。

Objective To carry out prenatal diagnosis for a fetus with normal ultrasonographic finding at 20 weeks’gestation but a copy number variant(CNV)of 13q indicated by non-invasive prenatal test(NIPT).Methods Karyotyping analysis and chromosomal CNV assay were carried out on the amniotic fluid sample.Parental peripheral blood sample was collected for chromosomal analysis.Detailed fetal ultrasound scan was carried out to rule out structural abnormalities of the fetus.Results The fetus was detected with a heterozygous 10.14 Mb deletion at 13q21.1q21.32,which has originated from the phenotypically normal mother.No apparent karyotypic abnormality was detected in the fetus and its parents.No ultrasonic abnormality was found in the fetus.Conclusion Both the fetus and its mother have carried a heterozygous 10.14 Mb deletion at 13q21.1q21.32 and presented normal phenotypes.Combined with literature review,the segmental deletion was judged to be a benign variant.