Resorbed co‐twin as an explanation for discrepant chorionic villus results: Non‐mosaic 47,XX, +16 in villi (direct and culture) with normal (46,XX) amniotic fluid and neonatal blood

Tharapel, Avirachan T.; Elias, Sherman; Shulman, L.P.; Seely, Linda; Emerson, Donald E.; Simpson, Joe Leigh

doi:10.1002/pd.1970090703

Cited by 81 publications

(36 citation statements)

References 10 publications

(13 reference statements)

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“…Identification of true mosaicism for trisomy 16 is not infrequently encountered during prenatal diagnosis, particularly in chorionic villus samples (CVS) [Hsu and Perlis, 1984;Hashish et al, 1989;Verp et al, 1989;Tharapel et al, 1989;Sundberg and Smidt-Jensen, 1991;Hajianpour et al, 1992;Post and Nijnuis, 19921. Huff et al 119911 described a prenatal diagnosis of trisomy 16 mosaicism in a fetus with VSD and some minor anomalies.…”

Section: Discussionmentioning

confidence: 99%

Variable clinical expression of mosaic trisomy 16 in the newborn infant

et al. 1993

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Trisomy 16 is common in embryos and fetuses aborted early during development. Mosaicism for trisomy 16 is sometimes encountered during prenatal diagnosis, particularly with chorionic villi biopsy specimens, and, until recently, was thought to be confined to the placenta. However, recently, several liveborn infants with trisomy 16 mosaicism have been described. We report on an additional liveborn infant with trisomy 16 mosaicism and compare the clinical findings with those of the previously reported cases in an attempt to delineate a mosaic trisomy 16 syndrome. Cytogenetic analysis from our patient showed that there was a different proportion of abnormal cells in different tissues and that the anomaly was undetectable in blood lymphocyte cultures. This observation was consistent with some of the previous reports. DNA analysis of parents and child was carried out using a polymorphic dinucleotide marker that maps to the long arm of chromosome 16. This analysis showed that the extra chromosome 16 in the infant was maternal in origin and suggested that the nondisjunction was probably a first meiotic division error. Our results suggest that an investigation of multiple tissues is required before concluding that mosaicism is confined to the placenta. We conclude that a finding of trisomy 16 mosaicism at prenatal diagnosis should be regarded with extreme caution. This diagnosis may be associated with a highly variable phenotype that may occasionally be compatible with extrauterine life.

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Section: Discussionmentioning

confidence: 99%

Variable clinical expression of mosaic trisomy 16 in the newborn infant

et al. 1993

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“…Chimerism In an early report of the prenatal detection of both trisomy 16 and normal cells, it was hypothesized that some cases might not in fact reflect mosaicism but rather chimerism with resorption of a deceased trisomic co-twin [Tharapel et al, 1989]. This explanation was supported by two cases in which both 47,XX,+16 and 69,XXX cell lines were identified Post and Nijhuis, 1992].…”

Section: Mechanisms For Abnormalitymentioning

confidence: 94%

“…This could represent an underestimate of the true incidence of trisomy 16 cells in CVS. Not all cases receive analysis of both cytotrophoblast and mesenchymal tissues, and trisomy 16 may be present in localized segments of placenta that are missed during random sampling [Tharapel et al, 1989;Henderson et al, 1996]. Table I summarizes published cases of first or second trimester diagnosis of trisomy 16 cells in chorionic villi analyses that were not attributable to nonmosaic confirmed trisomy 16.…”

Section: Chorionic Villimentioning

confidence: 96%

Trisomy 16 and trisomy 16 mosaicism: A review

Benn

1998

Am. J. Med. Genet.

142

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A review of all prenatal and postnatal diagnoses of trisomy 16 and trisomy 16 mosaicism was carried out in the context of the current understanding of confined placental mosaicism and uniparental disomy (UPD). The prenatal detection of trisomy 16 cells is associated with a high probability of fetal death, preterm delivery, intrauterine growth retardation, and fetal anomalies. Birth defects were typical of those seen in nonmosaic partial duplications of chromosome 16. Surprisingly, anomalies were sometimes limited to a single organ and included some relatively common isolated defects such as a ventricular septal defect, hypospadias, imperforate anus, inguinal hernia, and clubfoot. The risk for abnormality appeared to be higher in those pregnancies in which trisomy 16 cells were identified in amniotic fluid compared to the detection in chorionic villi samples. Contrary to nonmosaic trisomy 16 with an excess of males, mosaic trisomy 16 shows an excess of female karyotypes. Following the prenatal detection of trisomy 16 cells, aneuploid cells are almost never found in fetal or neonatal lymphocytes. Studies on fibroblasts also often fail to confirm the presence of the abnormal cell line even in cases in which multiple anomalies are present. It is likely that trisomy 16 cells are sometimes present in the early developing embryo even though subsequent cytogenetic studies on fetal or neonatal tissues may not detect any aneuploid cells. UPD can be excluded as a mechanism for those anomalies that are common to mosaic trisomy 16 and nonmosaic partial duplications. The term "occult mosaicism" is suggested to describe the situation in which the presence of an abnormal cell line is suspected on the basis of clinical data but unproven by laboratory analysis.

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“…Sometimes mosaicism, however, may lead to apparent nonmosaicism that is confined to one cell line due to (1) the nondisjunction event occurring late in development, or (2) random partitioning of the progenitor cells at the time of differentiation of new cell lines, or (3) sampling at the time of analysis. After long-term culture, which was the method used in this study, apparent nonmosaic chorionic villi in conceptuses with confined placental mosaicism (CPM) has been reported for 45X [Hogge et al, 19861 and trisomy 16 [Hogge et al, 1986;Tharapel et al, 1989;Verp et al, 1989;Sundberg and Smidt-Jensen, 1991; Williams et al, 19921. Although nonmosaic CPM for trisomy 16 has been detected several times at CVS, its frequency is unknown and nonmosaic CPM for trisomies 21, 18, and 13 has not been reported in studies using long-term culture.…”

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confidence: 91%

Cytogenetic evidence for enhanced selective miscarriage of trisomy 21 pregnancies with advancing maternal age

et al. 1992

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The effect of advancing maternal age on the risk of death of fetuses with certain chromosome abnormalities has been tested by comparing their frequency at the time of chorionic villus sampling (CVS) with that at amniocentesis. The frequency of chromosome abnormalities among women whose sole risk factor for a chromosome abnormality was advanced maternal age (> or = 35 years old) was determined in a pooled group of 15,147 CVS cases, of whom > 1/3 were from the initial 7,500 CVS cases at the University of California, San Francisco, and compared with a pooled group of 74,851 amniocentesis cases collected from the literature. The frequency of trisomy 21 not only increased with advancing maternal age as expected, but the slope of the increase was about 25% greater in the CVS group than in the amniocentesis group (P = 0.08 for the difference in slopes by a logistic statistical model and P = 0.04 by a normit model). Similar patterns were seen for trisomies 18 and 13, but the P values for the differences in slopes were much higher. These results suggest that the miscarriage rate of trisomy 21 during the gestational interval studied is selectively greater with advancing maternal age. The basis for the enhanced selective loss of trisomy 21 with maternal age may be a reduced ability of the ageing "maternal compartment" to compensate for abnormal conceptuses.

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Resorbed co‐twin as an explanation for discrepant chorionic villus results: Non‐mosaic 47,XX, +16 in villi (direct and culture) with normal (46,XX) amniotic fluid and neonatal blood

Cited by 81 publications

References 10 publications

Variable clinical expression of mosaic trisomy 16 in the newborn infant

Variable clinical expression of mosaic trisomy 16 in the newborn infant

Trisomy 16 and trisomy 16 mosaicism: A review

Cytogenetic evidence for enhanced selective miscarriage of trisomy 21 pregnancies with advancing maternal age

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