Quantitation of fetal DNA in maternal serum in normal and aneuploid pregnancies

We investigated whether the amount of circulating cell-free fetal DNA in maternal serum is influenced by fetal karyotype, using real-time quantitative polymerase chain reaction assay. Serum samples were obtained from pregnant women at gestational ages ranging from 15 to 17 weeks, prior to their undergoing amniocentesis. In total, we examined 70 samples consisting of 55 cases of pregnancy with 46,XY, 5 cases with 47,XY,+21, 3 cases with 47,XY,+18, a single case with 46,XY,dup(1) and 2 cases with twins of 46,XY, and 4 cases with 46,XX which were used as negative controls. We measured the concentration of the SRY sequence as a molecular marker for fetal DNA. The SRY sequence was detectable and measurable when the fetuses were male except for one case with 47,XY,+18. This case showed fetal growth retardation and bradycardia. No amplification signals of the SRY sequence were detected when the fetuses were female. The mean concentration of fetal DNA in maternal serum was 31.5 copies/ml in the pregnancy with 46,XY, 23.5 copies/ml in the pregnancies with 47,XY,+21 and 21.5 copies/ml in the pregnancies with 46,XY,+18. There were no significant differences in the concentration of fetal DNA between pregnancies with fetuses of normal karyotype and those with fetuses of abnormal karyotype.     

Additional chromosome in a child as a result of a balanced reciprocal translocation t(12;18)(p13;q12) in his mother's karyotype

In this case report we present a child with an additional chromosome in the karyotype. The karyotypes of the boy and his parents were analyzed by use of a conventional banding technique (GTG) and fluorescence in situ hybridization (FISH). Probes painting whole chromosomes 12 and 18 were used in FISH. Cytogenetic examination of the parents revealed that his mother was carrying balanced reciprocal translocation between chromosomes 12 and 18. Her karyotype was described as 46,XX,t(12;18)(p13;q12). Father's karyotype was normal, described as 46,XY. The boy's karyotype was defined as 47,XY,+der(18)t(12;18)(p13;q12). The additional chromosome appeared probably due to 3:1 meiotic disjunction of the maternal balanced translocation, known as tertiary trisomy. The mother displayed a normal phenotype and delivered earlier a healthy child. However, the boy with the unbalanced karyotype shows multiple congenital abnormalities.     

Mosaicism for trisomy 21 and ring (21) in a male born to normal parents: A case report

We present a case of a ring (21) in a mentally challenged patient with mosaicism for trisomy 21 showing karyotype 47, XY,+21/47,XY,+21(r)/46,XY, born to normal parents. The parents and female sibling were phenotypically normal. This is a unique case report from Central India, on occurrence of trisomy 21 and r (21) in the same individual born to normal parents. Also being documented for the first time is the immuno-FISH analysis revealing differential expression of hTERT and a linked over expression of TRF2 in proband, probably corresponding to a high percentage of acrocentric associations.     

A patient with tetrasomy 9p, Dandy-Walker cyst and Hirschsprung disease.

The authors report on a patient with tetrasomy 9p and 9qh due a karyotype 47,XY,+dic(9)(q12) in lymphocytes and a normal karyotype in fibroblasts. Clinical and complementary investigation revealed a malformation syndrome with many anomalies like those of trisomy 9p as well as Dandy-Walker cyst and Hirschsprung disease not previously described in tetrasomy 9p.     

Maternally transmitted extra ring(21) chromosome in a boy with Down's syndrome

Summary An 11-month-old boy with typical Down's syndrome is presented. His karyotype was 47,XY,+r(21); the erythrocyte superoxide dismutase-1 (SOD-1) activity was elevated. His phenotypically normal mother showed 46,XX,r(21) karyotype and normal SOD-1 activity. Analysis of chromosomal heteromorphism revealed that in addition to the ring, a normal chromosome 21 was transmitted from the mother.     

Rare case of XX/XY mosaicism and trisomy 13 in early prenatal diagnosis

Coexistence of XX/XY sex mosaicism and autosomal trisomy in prenatal diagnosis is particularly rare. Herein, we report the first, to our knowledge, case of a fetus with cyclopia, ambiguous genitalia and a 47,XX,+13,inv9[47]/47,XY,+13[13] karyotype detected at 13 weeks of gestation after chorionic villus sampling. Molecular analysis after prenatal diagnosis suggests that this is a case of sex mosaicism coexisting with trisomy 13, rather than chimera.     

Four new cases of X-autosome translocation in man (author's transl)]

Four new cases of translocations involving the X chromosome are reported. The first is a balanced t(1;X) observed in an abnormal girl. In most of the cells, the normal X is inactivated. The second case is a woman with oligomenorrhea, who has had two spontaneous abortions. She carries an umbalanced t(X-autosome). In all cells, the abnormal X, including the autosomal segment, is inactivated. The third and fourth cases are a mother, and her son. The mother has oligomenorrhea, carries a t(X,X), and has a karyotype of 46,X,+der t(X;X) and that of her son is 47,XY,+der t(X;X) and shows behavioral abnormalities. The abnormal X chromosome is inactivated in all the cells analyzed.     

Infertility and marker chromosomes: Application of molecular cytogenetic techniques in a case of inv dup(15)

We report on a phenotypically normal man with infertility, whose 47,XY,+mar karyotype was studied by spectral karyotyping (SKY) and fluorescence in situ hybridization (FISH) using a chromosome-15-specific probe (LSI SNRPN). By these techniques, the marker chromosome was identified as a small inv dup (15). Possible causes for male infertility in this case are discussed.     

Three interesting cases of Down's syndrome

The results of the cytogenetic study of three families that have children affected by Down's syndrome are presented. The karyotype of case 1 was 48,XY,+21,22s+,+mar; the marker chromosome had been produced "de novo". Case 2 was: 47,X,t(Xq21q), +t(21qXq); the abnormality had been produced "de novo". Case 3 was carrier of a homogeneous trisomy 21 (47,XY,+21), where the mother was carrier of a balanced translocation 13q14q. CBG, GTG, Ag-NOR, QFQ and FPG banding techniques were used to determine the origin and importance of these anomalies.     

A familial extra small marker autosome in persons with normal phenotype

The propositus was referred because of sterility and oligospermia. His karyotype was 45, XY, t(13q14q). His father was dead; his mother and the only brother, who was fertile, both had 47 chromosomes, but a normal phenotype and normal intelligence. The additional chromosome was three quarters the size of a G chromosome and had satellites on the short and long arms.     

Mosaic double aneuploidy: Down syndrome and XYY

Chromosomal abnormalities are seen in nearly 1% of live born infants. We report a 5-year-old boy with the clinical features of Down syndrome, which is the most common human aneuploidy. Cytogenetic analysis showed a mosaicism for a double aneuploidy, Down syndrome and XYY. The karyotype was 47, XY,+21[19]/48, XYY,+21[6]. ish XYY (DXZ1 × 1, DYZ1 × 2). Mosaic double aneuploidies are very rare and features of only one of the aneuploidies may predominate in childhood. Cytogenetic analysis is recommended even if the typical features of a recognized aneuploidy are present so that any associated abnormality may be detected. This will enable early intervention to provide the adequate supportive care and management.     

Prenatal molecular cytogenetic diagnosis of partial tetrasomy 10p due to neocentromere formation in an inversion duplication analphoid marker chromosome

Neocentromeres are fully functional centromeres found on rearranged or marker chromosomes that have separated from endogenous centromeres. Neocentromeres often result in partial tri- or tetrasomy because their formation confers mitotic stability to acentric chromosome fragments that would normally be lost. We describe the prenatal identification and characterization of a de novo supernumerary marker chromosome (SMC) containing a neocentromere in a 20-wk fetus by the combined use of comparative genomic hybridization (CGH) and fluorescence in situ hybridization (FISH). GTG-banding of fetal metaphases revealed a 47,XY,+mar karyotype in 100% of cultured amniocytes; parental karyotypes were both normal. Although sequential tricolor FISH using chromosome-specific painting probes identified a chromosome 10 origin of the marker, a complete panel of chromosome-specific centromeric satellite DNA probes failed to hybridize to any portion of the marker. The presence of a neocentromere on the marker chromosome was confirmed by the absence of hybridization of an all-human-centromere alpha-satellite DNA probe, which hybridizes to all normal centromeres, and the presence of centromere protein (CENP)-C, which is associated specifically with active kinetochores. Based on CGH analysis and FISH with a chromosome 10p subtelomeric probe, the marker was found to be an inversion duplication of the distal portion of chromosome 10p. Thus, the proband's karyotype was 47,XY,+inv dup(10)(pter-->p14 approximately 15::p14 approximately 15-->neo-->pter), which is the first report of partial tetrasomy 10p resulting from an analphoid marker chromosome with a neocentromere. This study illustrates the use of several molecular strategies in distinguishing centric alphoid markers from neocentric analphoid markers.     

Classical Prader-Willi syndrome with trisomy 15(pter----q12) plus de novo variant 15p11

We describe a boy with the classical Prader Willi syndrome (PWS), clinically, who had a chromosome abnormality not previously described in PWS. The karyotype was 47,XY,+mar, var(15)(p11). The marker was a fragment of 15 from 15pter----q12 and the variant 15p11 was de novo in origin. Overall, this karyotype contains increased 15 heterochromatin and we discuss alteration in the amount of 15 heterochromatin in PWS.     

Inheritance of a translocation between chromosomes 12 and 16 in a family with recurrent miscarriages and a newborn with Down syndrome carrying the same translocation

Reciprocal translocation carriers have reduced fertility, increased risk of spontaneous abortion or unbalanced karyotype in their offspring. Here, we report the inheritance of a translocation between chromosomes 12 and 16 in a family with recurrent miscarriages and a newborn with Down syndrome carrying the same translocation. Chromosomal analysis from fetal amniotic fluid and peripheral blood lymphocytes from the family were performed at the Cukurova university hospital in Turkey. We assessed a family in which the translocation between chromosomes 12 and 16 segregates; one of the eight progenies with the karyotype 47,XY,+21,t(12;16)(q24;q24) was heterozygote for the translocation and presented with Down syndrome. His mother is phenotypically normal, one brother and one sister were also carrying the same translocation. Apparently, this rearrangement occurred due to the unbalanced chromosome segregation of the mother [t(12;16)(q24;q24)mat]. This case will enable us to explain the behavior of segregation patterns and the mechanism for each type oftranslocation from carrier to carrier and their effects on reproduction and numerical aberrations. The t(12;16) is also associated with fetal wastage and may play a role in the etiology of the family's miscarriages. These findings can be used in clinical genetics and may be used as an effective tool for reproductive guidance and genetic counseling.     

Cell-cycle kinetics of cell lines from patients with chromosomal mosaicism

Lymphocyte cultures from five patients with chromosomal mosaicism (two 47,XY,+21/46,XY, one 47,XX,+21/46,XX, one 45,X/46,XX, and one 47,XXY/46,XY) were studied using sister chromatid differential staining technique for cell kinetic evaluation. Aneuploid and normal cell lines were compared to identify changes in cellular proliferation in vitro that could be related to cellular selective advantage and cell-line-proportion changes occurring with age. Comparison of the percentage of cells in different cell generations in 48, 72, and 96 h-cultures shows no differences between the aneuploid and normal cell lines indicating that cell-cycle kinetics is similar in these cells in vitro.     

The natural history of cytogenetically abnormal fetuses detected at midtrimester amniocentesis which are not terminated electively: new data and estimates of the excess and relative risk of late fetal death associated with 47,+21 and some other abnormal karyotypes.

We report the results of an ongoing survey of rates of spontaneous death of fetuses with chromosome abnormalities detected at second-trimester amniocentesis in which the mother did not elect abortion. Estimated excess risks (and conservative 90% confidence intervals) of spontaneous fetal death for various cytogenetic abnormalities are as follows: 47,+21, 25.6% (18.0%-34.0%); 47,+18, 63.8% (49.3%-79.8%); 47,+13, 36.5% (11%-69.7%); 45,X, 65.3% (41.0%-84.2%); and mosaic 45,X/46,XX, 10.8% (1.0%-26.8%). There is little evidence for an excess risk of fetal death, at least following amniocentesis, for 47,XXX, 47,XXY, or 47,XYY. The excess risks of fetal death were adjusted for the likelihood that a fetus of normal karyotype would undergo spontaneous fetal death in a population of older maternal age similar to that in which prenatal cytogenetic diagnosis is undertaken. The absolute fetal death rates when this factor is ignored are about 3.5% higher (i.e., may be derived by adding 3.5% to the values given). The excess risks are those which are most appropriate for use in estimating the contribution of chromosome abnormalities to spontaneous fetal death.     

Balanced structural changes involving the human X: Effect on sexual phenotype

Summary A normal cell line arising from a translocation, t(12;21), possibly by dissociation, was observed in two brothers in early life. Each was conceived as trisomic 21 by their 45,XY,-12,-21,+t(12;21) father, who was phenotypically normal. Each brother showed morphologic manifestations of trisomy 21 syndrome, and each was mildly mentally retarded. Dermatoglyphic indices were not diagnostic of trisomy 21 syndrome. At 4 months the younger brother had a 50:50 proportion of trisomic:normal blood cells which became 25:75 of trisomic 21:normal at 36 months. The older brother had a 25:75 proportion of trisomic 21:normal when first studied at 41/2 years. A similar t(12;21) has not previously been reported. The occurrence of an apparently normal cell line arising spontaneously is unique.     

Prenatal diagnosis of trisomy 9.

A male karyotype with trisomy 9 (47,XY,+9) was identified in amniotic fluid cells from a 40-year-old pregnant woman. After termination of the pregnancy by saline abortion, the cytogenetic diagnosis was confirmed in a cell line grown from placental tissue. Microscopic and gross pathological findings in the fetus were compared to 1 case with trisomy 9 and 3 with trisomy 9 mosaicism reported in the literature. A distinct clinical syndrome appears to be associated with this rare autosomal trisomy.     

Erroneous genetic sex determination of a newborn twin girl due to chimerism caused by foetal blood transfusion. A case report

OBJECTIVE: We present a case of erroneous sex determination in a newborn twin girl (twin A) due to chimerism. CASE REPORT: Amniocentesis and ultrasound examination had pointed towards male sex of both twins. At birth, twin A presented as a phenotypically normal female with 46,XY karyotype, and 46,XY gonadal dysgenesis was suspected. Twin B was a normal male. RESULTS: In our department, further examinations of twin A included undetectable testosterone and inhibin-B and elevated FSH. Ultrasound suspected an infantile uterus, and sequencing of the SRY gene was normal. After gonadectomy, a 46,XX karyotype was demonstrated in both normal infantile ovaries and in the fibroblasts from a skin biopsy. Analysis of X-linked markers in DNA from blood lymphocytes in both twins was identical, consistent with 46,XY karyotypes. CONCLUSION: Twin A is a 46,XX female with a chimeric 46,XY blood cell line due to intrauterine transfusion from her twin brother.     

Double aneuploidy in three Egyptian patients: Down-Turner and Down-Klinefelter syndromes

The co-occurrence of two numerical chromosomal abnormalities in same individual (double aneuploidy) is relatively rare and its clinical presentations are variable depending on the predominating aneuploidy or a combination effect of both. Furthermore, double aneuploidy involving both autosomal and sex chromosomes is seldom described. In this study, we present three patients with double aneuploidy involving chromosome 21 and sex chromosomes. They all had the classical non disjunction trisomy 21; that was associated with monosomy X in two of them and double X in the other. Clinically, they had most of the phenotypic features of Down syndrome as well as variable features characteristic of Turner or Klinefelter syndrome. Cytogenetic studies and fluorescence in situ hybridization (FISH) analysis were carried out for all patients and their parents. The first patient was a male, mosaic with 2 cell lines (45,X/47,XY,+21) by regular banding techniques and had an affected sib with Down syndrome (47,XY,+21). The second was a female, mosaic (46,X,+21/47,XX,+21) where monosomy X was detected only by FISH in 15 percentages of cells, nevertheless, stigmata of Turner syndrome was more obvious in this patient. The third patient had non mosaic double trisomy; Down-Klinefelter (48,XXY,+21) presented with Down syndrome phenotype. Parental karyotypes and FISH studies for these patients were normal with no evidence of mosaicism. In this report, we review the variable clinical presentations among the few reported cases with the same aneuploidy in relation to ours. Also, the proposed mechanisms of double aneuploidy and the occurrence of non-disjunction in more than one family member are discussed. This study emphasizes the importance of molecular cytogenetics studies for more than one tissue in cases with atypical features of characteristic chromosomal aberration syndromes. To our knowledge, this is the first report of double aneuploidy, Down-Turner and Down-Klinefelter syndromes in Egyptian patients.