• Biomedical Science Letters
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• v.17 no.2
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• pp.129-134
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• 2011

Mosaicism is the presence of two or more chromosomally distinct cell lines, each seen in two or more cells. Chromosomal mosaicism presents one of the most difficult problems in prenatal cytogenetic diagnosis, requiring the differentiation of true mosaicism from pseudomosaicism. To overcome associated problems we investigated 24 cases (amniotic fluid 13 cases, abortus tissue 3 cases, peripheral blood 8 cases) in which mosaicism has been found in cytogenetic analysis. 5 cases (38.5%) of 13 amniotic fluid cells in which mosaicisms showed single cell pseudomosaicism. Chromosomal true mosaicism is found in about 0.28% (8/2,826) of amniotic fluid cell cultures. The 24 cases involved 12 cases (50%) with sex chromosomal abnormalities, 7 cases (29.2%) with autosomal structural defects, 3 cases (12.5%) with autosomal abnormalities, 2 cases (8.3%) with a supernumerary marker. Mosaicism detected in amniotic fluid may represent the true mosaicism or may pseudomosaicism. If the same chromosome abnormality is seen in more than one cell and in two different cultures, it is considered a true mosaicism, whereas single-cell abnormalities from a single culture are regarded as pseudomosaicism. In this study, we describe a mosaicism in chromosome analysis, its diagnostic problems and clinical significance.

• Journal of Genetic Medicine
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• v.14 no.1
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• pp.31-33
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• 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
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• v.10 no.1
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• pp.52-56
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• 2013

Mosaic trisomy 14 syndrome is a well-known but unusual chromosomal abnormality with a distinct and recognizable phenotype. Array comparative genomic hybridization (CGH) analysis has recently become a widely used method for detecting DNA copy number changes, in place of traditional karyotype analysis. However, the array CGH shows a limitation for detecting the low-level mosaicism. Here, we report the detailed clinical and cytogenetic findings of patient with low-frequency mosaic trisomy 14, initially considered normal based on usual cut-off levels of array CGH, but confirmed by G-banding karyotyping. Our patient had global developmental delay, short stature, congenital heart disease, craniofacial dysmorphic features, and dark skin patches over her whole body. Estimated mosaicism proportion was 23.3% by G-banding karyotyping and 18.0% by array CGH.

• Journal of Genetic Medicine
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• v.10 no.2
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• pp.117-119
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• 2013

Double trisomy mosaicism of two different cell lines is extremely rare, particularly those that involve constitutional trisomy 8. We report a case of 47,XXX/47,XX,+8 in a 12-year-old female presenting with several skeletal anomalies. She exhibited distinct phenotypic features such as tall stature, deviation of the left middle finger, webbing of both thumbs and flexion deformities of the both third and fifth distal intermediate phalanges. A mild impulse-control disorder was observed, without mental retardation. Chromosomal and fluorescence in situ hybridization analysis demonstrated double trisomy mosaicism both on lymphocytes and buccal epithelial cells.

• Journal of Genetic Medicine
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• v.2 no.1
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• pp.1-5
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• 1998

A female hemihypertrophy patient with hypomelanosis of Ito is presented as a rare case combining classical features of both the syndrome. Chromosomal profile has been based on longitudinal study of repeated lymphocyte cultures during 1984-1992. The propositus has exhibited chromosomal mosaicism both hypoploid ($42{\pm}1$) and hyperploid ($48{\pm}2$ chromosome) counts, but the major stem line presented 46XX chromosomes. Ring chromosome with simple and complex translocations with marker dots appear to be the major cytogenetic assemblage of this child to posses unequal left and right halves of the body. Each and every organ from toe to the head has grown up unequally and lately the patient had been exhibiting different dark and light shapes of melanin on the skin. We believe that the patient had inherited, through her male parent, "a few" mutated loci on some chromosomes so as to generate different cell lines within the developing child. All sibs and the mother showed normal karyotype with no apparent aberration.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.92-92
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• 2003

Accurate analysis of nuclear status is needed when biopsied-blastomeres are used for embryo sexing. In this study, the nuclear status of blastomeres derived from 8- to 16-cell stage IVF bovine embryos was analyzed to evaluate the representative of single blastomere for embryo sexing. When 55 embryos were analyzed by PCR following biopsy, the coincident rate of sex determination between biopsied-single blastomere and matched blastocyst by PCR was 80 %. Karyotyping of biastomeres in 8- 16-cell stage bovine embryos was conducted to assess chromosome status of IVF embryos. To establish karyotyping of blastomeres, concentrations of vinblastine sulfate and duration of exposure time for metaphase plate induction with 8- to 16-cell stage bovine embryos were tested. The most effective condition for induction of metaphase plate (>45%) was 1.0 ug/ml vinblastine sulfate treatment for 15 h. In 22 embryos under the condition, only 8 embryos out of ten that had a normal diploid chromosome complement showed a sex-chromosomal composition of XX or XY (36.4%) and 2 diploid embryos showed mosaicism of the opposite sex of XX and XY in blastomeres of embryo (9.1%). One haploid embryo contained only one X-chromosome (4.5%). Four out of the other 11 embryos having a mixoploid chromosomal complement contained haploid blastomere with wrong sex chromosome (18.2%). These results suggested that morphologically normal bovine embryos derived from IVF had considerable proportion of mixoploid and sex-chromosomal mosaicism which could be the cause of discrepancies of the sex between biopsied-single blastomere and matched blastocyst by PCR analysis.

• Clinical and Experimental Pediatrics
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• v.46 no.6
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• pp.597-601
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• 2003

Trisomy 9 mosaic syndrome is a rarely reported chromosomal abnormality with high incidence of intrauterine growth retardation and perinatal death. Even a baby lives, he has severe mental retardation and significant malformations. The incidence and severity of malformations and mental retardation correlate with the percentage of trisomic cells in the different tissues. The characteristic craniofacial abnormalitis are narrow bifrontal diameter, up-slanted and short palpebral fissures, a prominent nasal bridge with a short root, a prominent lip covering a receding lower lip, low-set, posteriorly rotated, and misshapen ears. Ventricular septal defect is a main cardiac abnormality. Bony hypoplasia and dislocated hips have been frequently reported. Central nervous system, hepatobiliary, gastrointestinal and genitourinary abnormalities also had been reported. The authors report a baby who had characteristic abnormalities of trisomy 9 mosaicism with narrow temples, up-slanted palpebral fissures, a bulbous nose, thin and protruding upper lip, low set and malformed ears, hyperextended wrist and overlapping fingers. Cytogenetic analysis performed to confirm the chromosomal abnormality revealed trisomy 9, low level mosaic type.

• Clinical and Experimental Reproductive Medicine
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• v.19 no.1
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• pp.95-101
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• 1992

During the years 1983 to 1991, cytogenetic analysis was performed on 19 women with Turner syndrome in order to find out the incidence of symptoms and signs according to the classification of chromosome abnormalities. 1. All of them showed short stature and the mean height in 7 adults was $140.71{\pm}5.26cm$. 2. Among the 19 patients with Turner syndrome, 7 (36.8%) had 45, XO karyotype, 7 (36.8%) had 46, Xi (Xq), and remained 5 (26.3%) had mosaicism. 3. Five patients with mosaicism had 45, X/46, XX (2), 45, X/46, Xi (Xq) (2) and 45, X/47, XXX (1), respectively. 4. Patients with 45, XO and 46, Xi (Xq) had amenorrhea, whereas only 33% (1/3) of patients with mosaicism had amenorrhea. Total incidence of amenorrhea was 84.6% (11/13). 5. Abnormal external genitalia was detected in 63.6% of patients. The incidence of abnormality in patients with mosaicism was lower than that of other groups. 6. OMPC and deafness were detected in 3 of 19 patients. 7. Two cases of cardiovascular abnormalities were found in patients with 45, XO. This study suggests that gnenetic counselling according to the classification of chromosomal abnormalities could be needed in patients with Turner syndrome.

• Journal of Genetic Medicine
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• v.12 no.2
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• pp.118-122
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• 2015

Noninvasive prenatal test (NIPT) is a novel screening method for the diagnosis of fetal chromosomal aneuploidies. NIPT is based on technology that detects cell-free fetal DNA in maternal plasma and analyzes it with massively parallel sequencing technology to determine whether the fetus is at risk of trisomy 21, trisomy 18, trisomy 13 or sex chromosome abnormalities (SCAs). NIPT has been reported to have sensitivity of 99% and a false positive rate of less than 1% for detecting trisomy 21 and trisomy 18. Although extension of the application of NIPT to other SCAs has been attempted, there are concerns in extending NIPT to SCAs because of maternal or fetal mosaicism, undetected maternal SCAs, and multiple pregnancies. Recently, we assessed a pregnancy with the rare Turner syndrome mosaicism 45, X/47, XXX, which was reported as 45, X with NIPT. We present the case here and briefly review the current literatures on NIPT in testing for fetal monosomy X. To the best of our knowledge, this is the first report of the 45, X/47, XXX mosaicism in Korea to be reported as 45, X by NIPT with whole genome sequencing. This case report will provide valuable information for counseling women who want to undergo NIPT.

• Journal of Genetic Medicine
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• v.2 no.1
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• pp.7-10
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• 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.