Trisomy 13 ascertained in a survey of spontaneous abortions

Intrauterine growth retardation fetus with trisomy 16 mosaicism

Fetal trisomy 16 is considered uniformly lethal early in gestation. It has been reported to be associated with the variability of clinical features and outcomes. Mosaic trisomy 16 leads to a high risk of abnormality in prenatal cases. Intrauterine growth retardation (IUGR) is a common outcome of mosaic trisomy 16. Herein, we report on the case of Thai male IUGR fetus with trisomy 16 mosaicism. The fetal body was too small. Postmortem investigation of placenta revealed the abnormality including small placenta with furcated cord insertion and single umbilical cord artery. Cytogenetic study demonstrated trisomy 16 that was found 100% in placenta and only 16% in the fetal heart while other organs had normal karyotype. In addition, cardiac and other internal organs examination revealed normal morphology.

Miscarriage chromosome testing: utility of comparative genomic hybridization with reflex microsatellite analysis in preserved miscarriage tissue

OBJECTIVE

To assess the utility of comparative genomic hybridization (CGH) and reflex microsatellite analysis (MSA) for chromosome analysis of preserved miscarriage tissue.

DESIGN

Observational study.

SETTING

Academic recurrent pregnancy loss program.

PATIENT(S)

Patients with recurrent early pregnancy loss, defined as two or more miscarriages at <10 weeks, and at least one preserved miscarriage specimen sent for CGH.

INTERVENTION(S)

Preserved miscarriage specimens were sent for CGH. If results were euploid female (46,XX), reflex MSA was performed to assess if the result was of miscarriage or maternal origin.

MAIN OUTCOME MEASURE(S)

Results were recorded as either informative or uninformative. Uninformative results were classified as "CGH failed" or "maternal contamination."

RESULT(S)

Fifty-eight women with 77 miscarriage specimens met the criteria. CGH failed in nine of the preserved miscarriage specimens owing to minimal pregnancy tissue, and two owing to poor-quality DNA. Twenty-two of the 33 specimens reported as 46,XX by CGH were sent for MSA; maternal contamination was confirmed in 23% (5/22). CGH was therefore informative in 79% (61/77) of the specimens; 64% (39/61) were euploid, and 36% (22/61) were noneuploid, with a 46,XX/46,XY ratio of 2.5.

CONCLUSION(S)

CGH with reflex MSA is useful for obtaining chromosome results in preserved miscarriage specimens, although informative results were achieved in only 79% of specimens. Maternal contamination should be assessed after an initial diploid female result.

Placental expression of angiogenic factors in Trisomy 13

OBJECTIVE

Increased levels of soluble fms-like tyrosine kinase (sFlt-1) in Trisomy 13 pregnancies are thought to be mediated by the placenta. This study aimed to compare sFlt-1 expression in Trisomy 13 (n = 7) placentas with that in control placentas (Trisomy 21, n = 11, and euploid, n = 6).

STUDY DESIGN

This was a retrospective case-control study analyzing paraffin-embedded placental blocks that were stained with hematoxylin and eosin and antibodies to sFlt-1. Their staining intensity was compared using a semiquantitative technique. The Kruskal-Wallis test and Wilcox rank sum test were used for statistical analysis.

RESULTS

The median staining was significantly higher in Trisomy 13 compared with control specimens (P = .008) (for Trisomy 13 vs Trisomy 21, P = .003, and Trisomy 13 vs euploid, P = .004).

CONCLUSION

Our study demonstrates that Trisomy 13 placentas express more sFlt-1 than control placentas. These results strengthen the hypothesis that the increased incidence of preeclampsia in Trisomy 13 pregnancies is secondary to placental up-regulation of sFlt-1.

Secondary recurrent miscarriage and H-Y immunity

BACKGROUND

Approximately half recurrent miscarriage (RM) cases remain unexplained after standard investigations. Secondary RM (SRM) is, in contrast to primary RM, preceded by a birth, which increases the transfer of fetal cells into the maternal circulation. Mothers of boys are often immunized against male-specific minor histocompatibility (H-Y) antigens, and H-Y immunity can cause graft-versus-host disease after stem-cell transplantation. We proposed the H-Y hypothesis that aberrant H-Y immunity is a causal factor for SRM.

METHODS

This is a critical review of the H-Y hypothesis based on own publications and papers identified by systematic PubMed and EMBASE searches.

RESULTS

SRM is more common after the birth of a boy and the subsequent live birth rate is reduced for SRM patients with a firstborn boy. The male:female ratio of children born prior and subsequent to SRM is 1.49 and 0.76 respectively. Maternal carriage of HLA-class II alleles presenting H-Y antigens to immune cells is associated with a reduced live birth rate and increased risk of obstetric complications in surviving pregnancies in SRM patients with a firstborn boy. In early pregnancy, both antibodies against HLA and H-Y antigens are increased in SRM patients compared with controls. Presence of these antibodies in early pregnancy is associated with a lower live birth rate and a low male:female ratio in subsequent live births, respectively. Births of boys are also associated with subsequent obstetric complications in the background population.

CONCLUSIONS

Epidemiological, immunogenetic and immunological studies support the hypothesis that aberrant maternal H-Y immune responses have a pathogenic role in SRM.

Unbalanced and balanced acrocentric rearrangements involving chromosomes other than chromosome 21 at amniocentesis

OBJECTIVE

To investigate unbalanced and balanced acrocentric rearrangements involving chromosomes other than chromosome 21 at amniocentesis.

MATERIALS AND METHODS

From January 1987 to September 2009, 31,194 amniocenteses were performed at Mackay Memorial Hospital, Taipei, Taiwan. Two cases with unbalanced acrocentric rearrangements involving chromosomes other than chromosome 21 from two families, and 24 cases with balanced acrocentric rearrangements involving chromosomes other than chromosome 21 from 21 families were diagnosed and investigated.

RESULTS

We detected i(13q13q), +13 (one case), rob(13q14q), +13 (one case), rob(13q14q) (16 cases), rob(14q15q) (five cases), rob(13q15q) (one case), rob(15q22q) (one case), and mosaic rob(14q22q) (one case). Of the 25 cases that underwent parental cytogenetic investigation, six arose de novo and 19 were inherited (10 maternal and nine paternal). The 16 families with an inherited Robertsonian translocation included rob(13q14q) (11 families), rob(14q15q) (four families), and rob(15q22q) (one family). Of these 16 families, only two had known parental carrier status prior to the first amniocentesis, while the other 14 were aware of a parental carrier status only after prenatal diagnosis of a fetus with a heterologous Robertsonian translocation. The 18 fetuses with balanced heterologous Robertsonian translocations inherited them from six maternal carriers of rob(13q14q), four paternal carriers of rob(13q14q), four paternal carriers of rob(14q15q), and one maternal carrier of rob(15q22q). Neither UPD14 nor UPD15 was detected in any of the 16 cases tested for UPD.

CONCLUSION

Concerning acrocentric rearrangements involving chromosomes other than chromosome 21, we found a frequency of 0.0064% for unbalanced rearrangements and 0.0769% for balanced rearrangements at amniocentesis in this study. rob(13q14q) was the most common and rob(14q15q) the second most common rearrangement. Of the families with an inherited translocation, 87.5% were aware of parental carrier status only after prenatal diagnosis of a fetus with a translocation by amniocentesis.

Nonmosaic balanced homologous translocations of major clinical significance: some may be mosaic

The main mechanism proposed for formation of homologous translocations/isochromosomes is mitotic and if this occurs in a chromosomally normal conceptus, mosaicism would be expected to be seen. The lack of mosaicism in published cases of rearrangement (REA) of mitotic origin might be explained by under-detection due to the low level mosaicism for a normal line. Recently it was reported that sex-specific centromere instability in early embryogenesis leads to a female prevalence among individuals with mosaicism for pericentromeric rearrangements. To determine whether carriers of apparent non-mosaic homologous REA could be mosaics for a normal cell line, the sex ratio (male to female ratio) among carriers of balanced and unbalanced homologous translocations/isochromosomes was studied. This ratio was determined to establish if there is a female predominance similar to that seen in carriers of REA with mosaicism. In reviewing the literature, a female prevalence among fetuses with balanced homologous REA and among carriers of unbalanced homologous REA detected prenatally, postnatally and in miscarriages was found. Overall, there were 48 males and 72 females in the collected sample, and this ratio differed significantly from the expected sex ratio of 1.06 (P = 0.0075). There is not a male prevalence among miscarried fetuses, there is no evidence of selection against males in the collected material of this study. The analysis of sex ratios in different variants of trisomy 13 with respect to ascertainment (prenatal diagnosis, miscarriages, liveborn) also does not support an intrauterine selection against males as a cause of a female prevalence among carriers of homologous REA. Thus the data presented in this paper suggests that a proportion of the carriers of balanced homologous REA may have mosaicism for a normal line. Since low level mosaicism for a normal line in a translocation carrier would alter his/her reproductive options, it can be recommended that molecular polymorphic analysis be applied to these cases. This would allow those resulting from meiotic formation to be distinguished from those resulting from postzygotic formation. This latter mechanism may indicate the presence of a mosaicism for a normal line, making further intensive karyotypic analysis advisable. However, additional studies of healthy carriers of homologous REA of chromosome 14 or 15 should not be done. (c) 2007 Wiley-Liss, Inc.

Use of cross-species in-situ hybridization (ZOO-FISH) to assess chromosome abnormalities in day-6 in-vivo- or in-vitro-produced sheep embryos

Causes of chromosomal differences such as mosaicism between embryos developed in vivo and in vitro may be resolved using animal models to compare embryos generated in vivo with those generated by different production systems. The aims of this study were: (1) to test a ZOO-FISH approach (using bovine painting probes) to detect abnormal chromosome make-up in the sheep embryo model, and (2) to examine the extent of chromosome deviation in sheep embryos derived in vivo and in vitro. Cytogenetic analysis was performed on day 6 in-vivo and in-vitro derived sheep embryos using commercially available bovine chromosome painting probes for sex chromosomes X-Y and autosomes 1-29. A total of 8631 interphase and metaphase nuclei were analyzed from 49 in-vitro-derived and 51 in-vivo-derived embryos. The extent of deviation from normal ovine chromosome make-up was higher (p < 0.05) in in-vitro-produced embryos relative to in-vivo-derived embryos (65.3% vs. 19.6% respectively) mainly due to diploid-polyploid mosaicism. Polyploid cells ranged from 3n to 8 n with tetraploids most predominant among non-diploid cells. The proportions of polyploid cells per mixoploid embryo in in-vitro-produced embryos ranged from 1.4% to 30.3%, in contrast to less than 10% among the in-vivo-derived embryos. It was concluded that in-vitro-derived embryos are vulnerable to ploidy change compared to their in-vivo counterparts. The application of ZOO-FISH to domestic animal embryos is an effective approach to study the chromosome complement of species for which DNA probes are unavailable.

The chromosomal analysis of human oocytes. An overview of established procedures

The cytogenetic survey of mature human oocytes has been and remains a subject of great interest because of the prevalence of aneuploidy of maternal origin in abnormal human conceptuses, and the lack of understanding about the non-disjunction processes in human meiosis. The first attempts to analyse the chromosomal content of human female gametes were made in the early 1970s, and led to limited data because of the paucity of materials and the inadequacy of the procedure used. The years to follow brought a resurgence of interest in this field, because of the development of human IVF techniques which made oocytes unfertilized in vitro available for cytogenetic analysis. Numerous studies have since been performed. However, the difficulties in obtaining good chromosome preparations and of performing accurate chromosome identification have reduced the viability of these studies, resulting in large variations in the reported incidences of chromosomal abnormalities. The further introduction of new procedures for oocyte fixation and the screening of large oocyte samples have allowed more reliable data to be obtained and to identify premature chromatid separation as a major mechanism in aneuploidy occurrence. The last decade has been privileged to witness the adaptation of molecular cytogenetic techniques to human oocytes, and thus various powerful procedures have been tried not only on female gametes, but also on polar bodies, involving sequential and multicolour fluorescent in situ hybridization (FISH) labelling, comparative genomic hybridization (CGH), spectral karyotyping and alternative methods such as primed in situ labelling (PRINS) and peptide nucleic acid (PNA) techniques. A large body of data has been obtained, but these studies also display a great variability in the frequency of abnormalities, which may be essentially attributable to the technical limitations of these in situ methods when applied to human oocytes. However, molecular cytogenetic approaches have also evidenced the co-existence of both whole chromosome non-disjunction and chromatid separation in maternal aneuploidy. In addition, the extension of these techniques to oocyte polar body materials has provided additional data on the mechanism of meiotic malsegregation. Improvements of some of these techniques have already been reported. The further development of new approaches for the in situ analysis of human meiosis will increase the impact of cytogenetic investigation of human oocytes in the understanding of aneuploidy processes in humans.

Long-term survival in Patau syndrome

A female patient with an extra chromosome 13 (Patau syndrome) is described. There are only five previous reports of patients with trisomy 13 who have survived past the first decade. It is concluded that non-lethal congenital anomalies and aggressive medical care play an important role in the survival of patients with trisomy 13.

Molecular mechanisms for constitutional chromosomal rearrangements in humans

Cytogenetic imbalance in the newborn is a frequent cause of mental retardation and birth defects. Although aneuploidy accounts for the majority of imbalance, structural aberrations contribute to a significant fraction of recognized chromosomal anomalies. This review describes the major classes of constitutional, structural cytogenetic abnormalities and recent studies that explore the molecular mechanisms that bring about their de novo occurrence. Genomic features flanking the sites of recombination may result in susceptibility to chromosomal rearrangement. One such substrate for recombination is low-copy region-specific repeats. The identification of genome architectural features conferring susceptibility to rearrangements has been accomplished using methods that enable investigation of regions of the genome that are too small to be visualized by traditional cytogenetics and too large to be resolved by conventional gel electrophoresis. These investigations resulted in the identification of previously unrecognized structural cytogenetic anomalies, which are associated with genetic syndromes and allowed for the molecular basis of some chromosomal rearrangements to be delineated.

Pattern of malformations in the axial skeleton in human trisomy 13 fetuses

The purpose of this study was to analyse the development of the axial skeleton in human trisomy 13 fetuses and to define which fields in the axial skeleton are affected in this condition. We investigated nine human fetuses with trisomy 13 and gestational ages of 14-19 weeks. Whole body radiographs and radiographs of midsagittal tissue blocks of the cranial base and the spine were studied. In the youngest fetus, 14 w GA, no malformations were observed. In eight fetuses, 17-19 weeks GA, malformations occurred in the lumbosacral spine. In four fetuses additional malformations were observed in the thoracic spine. The study showed that there was a correspondence between the extent of malformation in the lumbosacral spine and the thoracic spine. When mild malformation occurred in the lumbosacral region, no malformation was observed in the thoracic region, whereas malformation was observed in the thoracic region when there was extensive malformation in the lumbosacral region. Malformations did not occur in the cervical spine or the basilar part of the occipital bone, but the postsphenoidal part of the sphenoid bone was small and irregular in the six cases where it could be examined. In seven fetuses there was malformation or agenesis of the nasal bone. This pattern of axial skeletal malformations in trisomy 13 fetuses was not described previously. Comparisons are made with previous studies of the fetal axial skeleton in trisomy 18 and trisomy 21, where the pattern of malformations was different. We reiterate our recommendation that axial skeletal radiography should be part of the postmortem examination of fetuses with suspected or verified chromosome abnormalities.

Sex ratios in fetuses and liveborn infants with autosomal aneuploidy

Ten data sources were used substantially to increase the available data for estimating fetal and livebirth sex ratios for Patau (trisomy 13), Edwards (trisomy 18), and Down (trisomy 21) syndromes and controls. The fetal sex ratio estimate was 0.88 (N = 584) for trisomy 13, 0.90 (N = 1702) for trisomy 18, and 1.16 (N = 3154) for trisomy 21. All were significantly different from prenatal controls (1.07). The estimated ratios in prenatal controls were 1.28 (N = 1409) for CVSs and 1.06 (N = 49427) for amniocenteses, indicating a clear differential selection against males, mostly during the first half of fetal development. By contrast, there were no sex ratio differences for any of the trisomies when comparing gestational ages < 16 and > 16 weeks. The livebirth sex ratio estimate was 0.90 (N = 293) for trisomy 13, 0.63 (N = 497) for trisomy 18, and 1.15 (N = 6424) for trisomy 21, the latter two being statistically different than controls (1.05) (N = 3660707). These ratios for trisomies 13 and 18 were also statistically different than the ratio for trisomy 21. Only in trisomy 18 did the sex ratios in fetuses and livebirths differ, indicating a prenatal selection against males > 16 weeks. No effects of maternal age or race were found on these estimates for any of the fetal or livebirth trisomies. Sex ratios for translocations and mosaics were also estimated for these aneuploids. Compared to previous estimates, these results are less extreme, most likely because of larger sample sizes and less sample bias. They support the hypothesis that these trisomy sex ratios are skewed at conception, or become so during embryonic development through differential intrauterine selection. The estimate for Down syndrome livebirths is also consistent with the hypothesis that its higher sex ratio is associated with paternal nondisjunction.

Uniparental isodisomy 13 in a normal female due to transmission of a maternal t(13q13q)

Chromosomes from a normal 23-year-old, primigravid woman were examined at 10 weeks of gestation because of her mother's history: 8 miscarriages and two liveborn infants (the proposita and a brother who died at 3 days with multiple anomalies). Karyotypes of the proposita and her normal mother were 45,XX,t(13q13q). No evidence of mosaicism was encountered. When the proposita inherited the t(13q13q), she received two copies of 13q from her mother. Moreover, she and her mother shared the same homozygous pattern of alleles from 7 highly polymorphic microsatellite repeats localized along 13q. No evidence of paternal markers from 13 was detected, although biparental inheritance was demonstrated with DNA markers from chromosomes 2 and 17. Cytogenetic and molecular findings indicated that the proposita's chromosomal complement included mUPD 13q. The proposita's normal phenotype suggested that no maternally imprinted genes map to 13q.

Molecular characterization of de novo secondary trisomy 13

Unbalanced Robertsonian translocations are a significant cause of mental retardation and fetal wastage. The majority of homologous rearrangements of chromosome 21 in Down syndrome have been shown to be isochromosomes. Aside from chromosome 21, very little is known about other acrocentric homologous rearrangements. In this study, four cases of de novo secondary trisomy 13 are presented. FISH using alpha-satellite sequences, rDNA, and a pTRI-6 satellite I sequence specific to the short arm of chromosome 13 showed all four rearrangements to be dicentric and apparently devoid of ribosomal genes. Three of four rearrangements retained the pTRI-6 satellite I sequence. Case 1 was the exception, showing a deletion of this sequence in the rearrangement, although both parental chromosomes 13 had strong positive hybridization signals. Eleven microsatellite markers from chromosome 13 were also used to characterize the rearrangements. Of the four possible outcomes, one maternal Robertsonian translocation, two paternal isochromosomes, and one maternal isochromosome were observed. A double recombination was observed in the maternally derived rob(13q13q). No recombination events were detected in any isochromosome. The parental origins and molecular chromosomal structure of these cases are compared with previous studies of de novo acrocentric rearrangements.

Nondisjunction of human acrocentric chromosomes: studies of 432 trisomic fetuses and liveborns

The present report summarizes molecular studies on the parent and meiotic stage of origin of the additional chromosome in 432 fetuses or liveborns with an additional chromosome 13, 14, 15, 21, or 22. Our studies suggest that there is little variation in the origin of nondisjunction among the five acrocentric trisomies and that there is no association between the origin of nondisjunction and the likelihood of survival to term of the trisomic conceptus. The proportion of cases of paternal origin was similar among the five trisomies: 12% for trisomy 13, 17% for trisomy 14, 12% for trisomy 15, 9% for trisomy 21, and 11% for trisomy 22. The stage of nondisjunction was also similar among the five trisomies, with the majority of cases of maternal origin being due to nondisjunction at meiosis I, whereas for paternally derived cases, nondisjunction occurred primarily at meiosis II.

Overexpression of esterase D in kidney from trisomy 13 fetuses

Human trisomy 13 (Patau syndrome) occurs in approximately 1 in 5,000 live births. It is compatible with life, but prolonged survival is rare. Anomalies often involve the urogenital, cardiac, craniofacial, and central nervous systems. It is possible that these abnormalities may be due to the overexpression of developmentally important genes on chromosome 13. The expression of esterase D (localized to chromosome 13q14.11) has been investigated in both muscle and kidney from trisomy 13 fetuses and has been compared with normal age- and sex-matched fetal tissues, by using northern analysis. More than a twofold increase in expression of esterase D was found in the kidney of two trisomy 13 fetuses, with normal levels in a third. Overexpression was not seen in the muscle tissues from these fetuses.

Triple autosomal trisomy in a pregnancy at risk for Bloom's syndrome

Cytogenetic analysis of the products of conception in a pregnancy at risk for Bloom's syndrome (BS) documented the karyotype 49,XX, +2, +8, +11. Autosomal triple trisomy has previously been reported in abortuses but is exceedingly rare. Other interesting but previously unreported observations made during the present study were the following: BS in a Brazilian individual, the first instance of BS diagnosed in South America; transmission of the BS mutation in Jews that are non-Ashkenazi; a medulloblastoma in the propositus, the first malignant brain tumor reported in BS; and, as in all previously examined pregnancies at risk for BS, non-homozygosity for the BS mutation.

Trisomy 13 syndrome and neural tube defects

Abnormalities of the CNS, such as arhinencephaly or holoprosencephaly, are common findings in trisomy 13 syndrome. However, neural tube defects (NTDs) are rarely reported. A review of 267 patients in the literature on reported CNS developmental defects in trisomy 13 syndrome showed only 6 patients with lumbosacral NTDs. No case of encephalocele or anencephaly was found. We report on 3 patients with spina bifida from the records of 34 necropsies of karyotyped trisomy 13 syndrome, which were found among 403,710 births.

Trisomy 13 in the fetus

A significant number of fetuses with trisomy 13 are spontaneously or voluntarily lost before birth; however, very few such fetuses have been systemically autopsied. In the present study, ten trisomy 13 fetuses of 130-305 mm in crown-rump length, estimated gestational age from 108 days to 239 days, were examined following either karyotype or ultrasonographic diagnosis and voluntary termination. Mean maternal age was 35.1 years. The spectrum of anatomical features was similar to that observed in neonates or older infants with trisomy 13, namely, holoprosencephaly, cyclopia, microphthalmia, cleft palate and lip, cardiac defect, polydactyly, and cystic kidney. Kidney weights were significantly increased above normal in eight of nine fetuses. Histologically, the cortex of these kidneys showed increased mitotic activity and blastemic appearance, which extended deep into the medullary areas. The weights and histology of other organs were normal except for slight increases in spleen weight.

Cytogenetic studies of couples with repeated spontaneous abortions of known karyotype

Several cytogenetic studies have reported an increased frequency of aneuploidy in peripheral blood cultures of couples with multiple spontaneous abortions. However, in none of the studies have the chromosome constitutions of the fetuses been known, making it difficult to interpret these observations. In the present study, we summarize our cytogenetic observations on 23 couples with multiple miscarriages, 12 of whom had repeated chromosomally normal spontaneous abortions, and 11 repeated trisomic spontaneous abortions. We were unable to demonstrate a significant difference in the level of aneuploidy between the two groups. Therefore, it seems unlikely that aneuploidy detectable in peripheral blood preparations is an important indicator of fetal aneuploidy.

Cytogenetic and molecular studies of trisomy 13

Chromosome heteromorphisms, restriction fragment length polymorphisms, or both were used to study the parental origin of 33 cases of simple trisomy 13 and eight cases of translocation trisomy 13. The most common origin for the simple trisomies was non-disjunction at maternal meiosis I, while for the translocations an equal number of paternally and maternally derived cases was observed. In seven of the simple trisomies, information was obtained from both the cytogenetic and molecular markers, making it possible to study recombination between the two non-disjoined chromosomes. Five of the seven cases involved errors at meiosis I, with crossing over being detected in two of three cases of maternal origin and in one of two cases of paternal origin. This indicates that absence of recombination because of pairing failure is unlikely to be of major importance in the genesis of trisomy 13.