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Abstract
The incidence of chromosome anomalies in newborn infants is 0.7-0.8 %. The phenotypic manifestations of chromosomal abnormalities are highly diverse. These anomalies may be present in phenotypically normal individuals in whom they can increase the risk of recurrent miscarriage and birth defects and/or mental retardation. It is important to determine this risk to provide patients with appropriate genetic counseling.
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Affiliation(s)
- M Moreno García
- Servicio de Genética, Hospital 12 de Octubre, Madrid, Spain.
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Velissariou V, Antoniadi T, Gyftodimou J, Bakou K, Grigoriadou M, Christopoulou S, Hatzipouliou A, Donoghue J, Karatzis P, Katsarou E, Petersen MB. Maternal uniparental isodisomy 20 in a foetus with trisomy 20 mosaicism: clinical, cytogenetic and molecular analysis. Eur J Hum Genet 2002; 10:694-8. [PMID: 12404100 DOI: 10.1038/sj.ejhg.5200867] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2002] [Revised: 06/24/2002] [Accepted: 06/28/2002] [Indexed: 11/09/2022] Open
Abstract
The clinical significance of trisomy 20 mosaicism detected prenatally remains uncertain due to the rarity of liveborn cases with inconsistent clinical findings, and lack of long-term follow-up and outcome. We describe a case of true trisomy 20 mosaicism in a liveborn girl with maternal uniparental isodisomy of chromosome 20 in the diploid blood cells. Trisomy 20 mosaicism was originally detected in amniotic fluid (98%) and was confirmed in the term placenta (100%), as well as in the blood (10%) and urine sediment (100%) of the neonate. There was intrauterine and postnatal growth retardation, but otherwise the newborn manifested no gross abnormalities. At 9 months of age moderate psychomotor retardation, central hypotonia with peripheral hypertonia, numerous minor morphogenetic variants, marked kyphosis, and extensive Mongolian spot were observed. To our knowledge this represents the first case of trisomy 20 mosaicism detected prenatally and confirmed in different tissues of the newborn, where uniparental disomy was demonstrated in the diploid cell line. The clinical and laboratory findings in our patient are compared with those of five previously reported cases of UPD20, suggesting that maternal UPD20 might be associated with a characteristic phenotype.
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Affiliation(s)
- Voula Velissariou
- Cytogenetics Laboratory, Department of Genetics and Molecular Biology, Mitera Maternity and Surgical Center, Athens, Greece
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Steinberg Warren N, Soukup S, King JL, St. J. Dignan P. Prenatal diagnosis of trisomy 20 by chorionic villus sampling (CVS): a case report with long-term outcome. Prenat Diagn 2002. [DOI: 10.1002/pd.169] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
Maternal uniparental disomy (UPD) 20 was found in a 35-month-old girl, the product of a pregnancy complicated by a prenatal diagnosis of mosaic trisomy 20. Phenotypic abnormalities included pre- and postnatal growth failure, microcephaly, minor dysmorphic features and psychomotor developmental delay. Chromosomal analysis on cord blood revealed only a normal 46,XX karyotype. Microsatellite analysis of 27 chromosome 20 loci confirmed maternal UPD for all 11 informative markers. Maternal heterodisomy was detected in two and maternal isodisomy in three loci. In the remaining six loci, a non-informative maternal UPD pattern was displayed, as mother and proband are homozygous for the same allele. To our knowledge this is the first reported case of maternal disomy 20 with normal karyotype ascertained by a mosaic trisomy 20 pregnancy.
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Affiliation(s)
- I S Salafsky
- Division of Genetics, Evanston Hospital, Northwestern University Medical School, Evanston, IL 60201, USA
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Pfeiffer RA, Ulmer R, Rauch A, Trautmann U, Beinder E, Rupprecht T, Mayer U, Steinkirchner B, Wündisch GF. True fetal mosaicism of an isochromosome of the long arm of a chromosome 20: the dilemma persists. Prenat Diagn 1997; 17:1171-5. [PMID: 9467815 DOI: 10.1002/(sici)1097-0223(199712)17:12<1171::aid-pd181>3.0.co;2-k] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We report the prenatal findings of mos 46,XY/46,XY,i(20q) after amniocentesis. The propositus presented with two epidermal scalp scars, retrobulbar orbital cysts, and dyssegmentation of the thoracic spine. The abnormal cell line was discovered in cells cultured from the proximal umbilical cord and--by fluorescence in situ hybridization (FISH)--in interphase nuclei from buccal epithelium and urinary sediment but not from the placenta, lymphocytes, or skin fibroblasts.
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Abstract
We report a case of mosaic trisomy 20, the most common autosomal mosaicism identified in amniocytes, ascertained in a woman referred for amniocentesis because of abnormal ultrasound at 18.1 weeks' gestation which revealed short femurs and nuchal thickening. Metaphase analysis of 98 clones revealed 47,XY, +20 in 96 cells (98 per cent). Trisomy 20 was demonstrated in 6 cells (12 per cent) in a total of 50 cells from two fetal blood cultures obtained after pregnancy termination. Fluorescence in situ hybridization (FISH) analysis of interphase nuclei utilizing a chromosome 20 alpha-satellite centromeric DNA probe revealed three signals in 57/546 nuclei (10 per cent) in fetal blood. Metaphase analysis of 167 cells from seven different fetal tissue sources revealed trisomy 20 in 32 cells (19.2 per cent). The percentage of trisomy 20 cells varied with tissue type, with the highest percentage (13/25 cells, 52 per cent) identified in the small intestine and lymph nodes and the lowest percentage (1/34 cells, 2.9 per cent) identified in a specimen of chorionic villi. Molecular genetic analyses utilizing polymerase chain reaction (PCR)-formated dinucleotide repeat polymorphisms demonstrated that the non-disjunctional event most likely occurred post-zygotically and that the origin of the extra chromosome 20 was maternal. This study is the first to demonstrate trisomy 20 cells in fetal blood, suggesting that mosaic trisomy 20 can be embryonic in origin. In cases of prenatally detected mosaic trisomy 20, examination of fetal blood should be considered, as well as study of placental membranes, skin, and urine sediment to confirm the karyotype and determine its significance.
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Affiliation(s)
- M A Micale
- Department of Genetics, Case Western Reserve University School of Medicine, Cleveland, OH, USA
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8
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Abstract
We report on 2 fetuses with prenatally diagnosed mosaic isochromosome 20q in amniotic fluid. Neither had an identifiable cytogenetic abnormality after birth. One infant developed a benign intracranial dermoid cyst at age 8 months. The other was completely normal in all respects. We are aware of 13 fetuses with this prenatally diagnosed chromosome finding; all fetuses tested have had normal chromosomes on subsequent cytogenetic studies and all, except one, have been morphologically normal. Fetuses with mosaic isochromosome 20q identified on amniocentesis are most likely to be phenotypically and cytogenetically normal after birth.
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Affiliation(s)
- A E Donnenfeld
- Department of Obstetrics and Gynecology, Pennsylvania Hospital, Philadelphia 19107
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9
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Abstract
A new case of prenatally detected mosaic trisomy 20 (79% trisomy 20 cells in amniocyte cultures) that was confirmed in newborn tissue is presented. A healthy male infant was delivered at term, with no dysmorphology or apparent malformations; this baby is developing normally. Twenty-five percent of foreskin and 17% of fetal cord cells also showed trisomy 20, while no trisomic cells were detected in newborn blood. High frequency mosaicism for trisomy 20 in this case was thus due to true embryonic origin. Extensive counseling and prenatal follow-up in this case led to an unaffected liveborn, and guarded optimism may be warranted for future cases of mosaic trisomy 20 detected prenatally.
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Affiliation(s)
- A R Brothman
- Department of Pediatrics, Eastern Virginia Medical School
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Richkind KE, Mahoney MJ, Evans MI, Willner J, Douglass R. Prenatal diagnosis and outcomes of five cases of mosaicism for an isochromosome of 20q. Prenat Diagn 1991; 11:371-6. [PMID: 1924178 DOI: 10.1002/pd.1970110605] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Five cases of mosaicism for an isochromosome of 20q have been detected from a total of 50,000 cases analysed for prenatal diagnosis by amniocentesis. Karyotypes were designated mos 46,X-/46,X-,i(20q). In all cases, the abnormal cell line was detected in more than one primary culture, thus fulfilling the criterion for true (level III) mosaicism. Indications for prenatal diagnosis were parental anxiety (two cases), low maternal serum alpha-fetoprotein (AFP) (two cases), and high maternal serum AFP (one case). Level II ultrasounds on all five fetuses were normal, and the abnormal cell line was never detected in fetal blood and/or cord blood. All five pregnancies were continued and had normal outcomes, with birth weights ranging from 2.4 to 3.8 kg. The development of all five children has been normal, with the oldest child in the study now 4 years of age. We suggest that the abnormal cell line in each case was of extrafetal origin, and that this may be one of the more common examples of this phenomenon, occurring in approximately 1/10,000 prenatal diagnoses. Mosaicism i(20q) may have been missed in the past because of the higher resolution necessary to detect this subtle change.
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Abstract
One hundred and three cases with prenatal diagnosis of trisomy 20 mosaicism through amniocentesis were reviewed. Approximately 90 per cent (90/101) of the cases were associated with grossly normal phenotype. It is likely that, in the majority of cases, cells with trisomy 20 were extraembryonic in origin or largely confined to the placenta. However, in some cases, the cells with trisomy 20 were confined to certain specific fetal organs or tissues such as kidney, skin, etc. Cytogenetic follow-up studies in liveborns should include a culture from urine sediment.
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Affiliation(s)
- L Y Hsu
- Prenatal Diagnosis Laboratory of New York City, NY 10016
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