PDF(Pubmed)
Abstract：
BACKGROUND: Chromosome 18p deletion syndrome is caused by total or partial deletion of the short arm of chromosome 18 and associated with cognitive impairment, growth retardation and mild facial dysmorphism. However, most studies on the genotype-phenotype correlations in the 18p region are diagnosed postnatally. Prenatal reports involving 18p deletions are limited.
METHODS: Three pregnant women opted for invasive prenatal testing due to noninvasive prenatal testing indicating high risk for chromosome 18 abnormalities. Karyotypic analysis and chromosomal microarray analysis (CMA) were performed simultaneously. The pregnancy outcomes for all cases were followed up. Meanwhile, we also made a literature review on prenatal phenotypes of 18p deletions.
RESULTS: G-banding analysis showed that 2 fetuses presented abnormal karyotypes: 45,XN,der(18)t(18;21)(p11; q11),-21 (case 2) and 46,XN,18p- (case 3). The karyotype of case 1 was normal. Meanwhile, CMA detected 4.37 Mb (case 1), 7.26 Mb (case 2) and 14.97 Mb (case 3) deletions in chromosome 18p region. All 3 pregnancies were terminated finally according to genetic counseling based upon abnormal CMA results.
CONCLUSIONS: Prenatal diagnosis of 18p deletion syndrome is full of challenges due to the phenotypic diversity, incomplete penetrance and lack of prenatal phenotypes. Increased nuchal translucency and holoprosencephaly are common prenatal phenotypes of distal 18p deletion. For fetuses carrying 18p deletions with atypical sonographic phenotypes, noninvasive prenatal testing could be adopted as an effective approach.
METHODS: Three pregnant women opted for invasive prenatal testing due to noninvasive prenatal testing indicating high risk for chromosome 18 abnormalities. Karyotypic analysis and chromosomal microarray analysis (CMA) were performed simultaneously. The pregnancy outcomes for all cases were followed up. Meanwhile, we also made a literature review on prenatal phenotypes of 18p deletions.
RESULTS: G-banding analysis showed that 2 fetuses presented abnormal karyotypes: 45,XN,der(18)t(18;21)(p11; q11),-21 (case 2) and 46,XN,18p- (case 3). The karyotype of case 1 was normal. Meanwhile, CMA detected 4.37 Mb (case 1), 7.26 Mb (case 2) and 14.97 Mb (case 3) deletions in chromosome 18p region. All 3 pregnancies were terminated finally according to genetic counseling based upon abnormal CMA results.
CONCLUSIONS: Prenatal diagnosis of 18p deletion syndrome is full of challenges due to the phenotypic diversity, incomplete penetrance and lack of prenatal phenotypes. Increased nuchal translucency and holoprosencephaly are common prenatal phenotypes of distal 18p deletion. For fetuses carrying 18p deletions with atypical sonographic phenotypes, noninvasive prenatal testing could be adopted as an effective approach.
摘要：
背景：染色体18p缺失综合征是由18号染色体短臂的全部或部分缺失引起的，并与认知障碍有关，生长迟缓和轻度面部畸形。然而,大多数关于18p区域基因型-表型相关性的研究都是在出生后诊断的.涉及18p缺失的产前报告有限。
方法：三名孕妇选择了侵入性产前检测，因为非侵入性产前检测表明18号染色体异常的高风险。同时进行核型分析和染色体微阵列分析（CMA）。随访所有病例的妊娠结局。同时,我们还对18p缺失的产前表型进行了文献综述。
结果：G带分析显示2个胎儿呈现异常核型：45，XN，der（18）t（18；21）（p11；q11），-21（案例2）和46，XN，18p-（案例3）。病例1的核型正常。同时,CMA检测到4.37Mb（案例1），染色体18p区缺失7.26Mb(病例2)和14.97Mb(病例3)。根据CMA异常结果，根据遗传咨询最终终止所有3次妊娠。
结论：由于表型多样性，18p缺失综合征的产前诊断充满挑战，不完全外显率和缺乏产前表型。颈透明层增加和全前脑是远端18p缺失的常见产前表型。对于携带具有非典型超声表型的18p缺失的胎儿，无创产前检测可作为一种有效的方法。
方法：三名孕妇选择了侵入性产前检测，因为非侵入性产前检测表明18号染色体异常的高风险。同时进行核型分析和染色体微阵列分析（CMA）。随访所有病例的妊娠结局。同时,我们还对18p缺失的产前表型进行了文献综述。
结果：G带分析显示2个胎儿呈现异常核型：45，XN，der（18）t（18；21）（p11；q11），-21（案例2）和46，XN，18p-（案例3）。病例1的核型正常。同时,CMA检测到4.37Mb（案例1），染色体18p区缺失7.26Mb(病例2)和14.97Mb(病例3)。根据CMA异常结果，根据遗传咨询最终终止所有3次妊娠。
结论：由于表型多样性，18p缺失综合征的产前诊断充满挑战，不完全外显率和缺乏产前表型。颈透明层增加和全前脑是远端18p缺失的常见产前表型。对于携带具有非典型超声表型的18p缺失的胎儿，无创产前检测可作为一种有效的方法。
