• Journal of Genetic Medicine
• /
• 제14권1호
• /
• pp.31-33
• /
• 2017

Chromosomal loss in trisomy (trisomy rescue) to generate a disomic fetus can cause confined placental mosaicism and/or feto/placental mosaicism. After trisomy rescue event, there is a risk of fetal uniparental disomy (UPD). Noninvasive prenatal test (NIPT) reflects the genomic constitution of the placenta, not of the fetus itself. Feto-placental discrepancy can therefore cause false-positive (trisomy) NIPT results. These discordant NIPT results can serve as important clues to find UPD associated with confined placental mosaicism. We report a case with maternal UPD of chromosome 20, detected by NIPT of 1,000 high-risk pregnancies, carried out for detecting chromosomal abnormalities in Koreans.

• Journal of Genetic Medicine
• /
• 제2권1호
• /
• pp.7-10
• /
• 1998

The present report describes a case that showed a normal fetal karyotype in an antenatal genetic study but an abnormal placental karyotype of 46,XX,r (15) on postnatal examination. The pregnancy was complicated by fetal nuchal translucency in the first trimester and intrauterine growth restriction in the second and third trimesters. A 1780 gm female baby was born after 40 weeks of gestation, but died of respiratory distress and sepsis on the 10th day of life. Our case was unique in that the placental chromosomal aberration was a structural abnormality instead of a numerical aberration that is seen in most reported cases of confined placental mosaicism.

• Journal of Genetic Medicine
• /
• 제8권1호
• /
• pp.35-43
• /
• 2011

목적: 본원에서 최근 10년간 시행한 융모막 융모생검의 적응증에 따른 결과 및 합병증을 조사하고 현재 사용하고 있는 융모막 융모생검의 효용성을 분석해보고자 한다. 대상 및 방법: 2000년 4월부터 2010년 4월까지 최근 10년간 분당차병원 및 강남차병원에서 융모막 융모생검을 시행한 511례의 진료기록 및 검사 결과를 검토하였다. 각각의 환자에 해당되는 모든 적응증을 조사하고 중복을 허용하여 분석하였다. 태아 염색체 검사는 직접법과 배양법을 통하여 시행하였다. 결과: 각각의 적응증을 살펴보면 태아의 비후된 목덜미 두께를 포함한 비정상 초음파 소견이 294례(294/635, 46.3%)로 가장 높았다. 각각의 적응증에 따른 태아 염색체 이상의 양성예측도는 부모 중에 염색체 이상이 있는 경우가 66.7%(14/21)로 가장 높았다. 융모막 융모생검 상 모자이시즘은 3.1% (16/509)였고, 그 중에서 양수검사로 확인된 진모자이시즘은 2례, 태반에 국한된 모자이시즘은 11례였다. 융모막 융모생검 이후 4주 이내에 임신 종결된 경우는 6례로 태아손실률은 1.2% (6/511)였다. 결론: 융모막 융모생검은 산전 유전진단을 하는데 있어서 적합하고 신뢰할 수 있는 시술이다. 융모막 융모생검 결과 모자이시즘을 보이는 경우 반드시 양수검사를 통하여 진모자이시즘인지 태반에 국한된 모자이시즘인지 확인이 필요하다.

• Journal of Genetic Medicine
• /
• 제12권2호
• /
• pp.61-65
• /
• 2015

Whole genome sequencing (WGS)-based noninvasive prenatal test (NIPT) is the first method applied in the clinical setting out of various NIPT techniques. Several companies, such as Sequenom, BGI, and Illumina offer WGS-based NIPT, each with different technical and bioinformatic approaches. Sequenom, BGI, and Illumina utilize z-, t-, and L-scores, as well as normalized chromosome values, respectively, for trisomy detection. Their outstanding performance has been demonstrated in clinical studies of more than 100,000 pregnancies. The sensitivity and specificity for detection of trisomies 13, 18, and 21 were above 98%, as reported by all three companies. Unlike other techniques, WGS-based NIPT can detect other trisomies as well as clinically significant segmental duplications/deletions within a chromosome, which could expand the scope of NIPT. Incorrect results could be due to low fetal fraction, fetoplacental mosaicism, confined placental mosaicism or maternal copy number variation (CNV). Among those, maternal CNV is a significant contributor of false positive results and therefore genome wide scanning plays an important role in preventing the occurrence of false positives. In this article, the bioinformatic techniques and clinical performance of three major companies are comprehensively reviewed.