Cytogenetic results of amniocentesis materials: incidence of abnormal karyotypes in the Turkish collaborative study

The experience on prenatal chromosome diagnosis of four Turkish centers participating in a collaborative study on 6041 genetic amniocentesis performed during a 4-8 years period were reviewed. 5887 (97.5%) patients had strong clinical indications for prenatal chromosome studies and 154 (2.5%) were referred because of maternal anxiety and a bad history of previous gestations. The main indication groups were: advanced maternal age (3197 cases), positive serum screening (2011 cases), ultrasound-identified anomaly (492 cases), previous fetus/child with chromosomal aberrations (103 cases), a history of a previous abnormal and/or mentally handicapped child (70 cases) and a parental chromosome rearrangement (14 cases). The average maternal age was 33.9 years and average gestational age was 18 weeks. A total of 179 affected fetuses were detected in this collaborative study (3%) of which 133 were unbalanced (74.3%). Among the 124 (69%) numerical aberrations, 102 (82.3%) were autosomal aneuploidies, 20 (16.1%) were gonosomal aneuploidies and 2 (1.6%) were poliploidies. Among the 55 (31%) structural aberrations, balanced translocation was the most common (63.6%) and 11 cases of inversion, four cases of unbalanced translocation, two cases of marker chromosome and three cases of other abnormalities were found. The overall culture success rate was 99.7%. Pregnancy termination that is permitted by legal authorities was accepted by 94.7% (126/133) with parents at unbalanced cytogenetic result announcement.

Mosaicism for terminal deletion of 4q

Chromosomal imbalance affecting the long arm of chromosome 4 has been reported in a variety of distinct clinical conditions. Common clinical findings have been described for 4q deletions distal to 4q33 and termed as 4q terminal deletion syndrome. We report two children with de novo chromosomal abnormality consisting of a terminal deletion (q33qter) of chromosome 4 in mosaic form. The phenotypes of these two patients are very similar to that described in the literature, but milder because of the mosaic nature of cytogenetic abnormality.

Neonatal management of trisomy 18: Clinical details of 24 patients receiving intensive treatment

Management of neonates with trisomy 18 is controversial, supposedly due to the prognosis and the lack of precise clinical information concerning efficacy of treatment. To delineate the natural history of trisomy 18 managed under intensive treatment, we reviewed detailed clinical data of 24 patients with full trisomy 18 admitted to the neonatal intensive care unit of Nagano Children's Hospital, providing intensive treatment to those with trisomy 18, from 1994 to 2003. Cesarean, resuscitation by intubation, and surgical operations were performed on 16 (67%), 15 (63%), and 10 (42%) of the patients, respectively. Mechanical ventilation was required by 21 (88%), and 6 (29%) of them were extubated. Survival rate at age 1 week, 1 month, and 1 year was 88%, 83%, and 25%, respectively. Median survival time was 152.5 days. Respiration was not stabilized in two patients with left diaphragmatic eventration and hypoplasia accompanied by lung hypoplasia, even with maximal ventilation. The common underlying factors associated with death were congenital heart defects and heart failure (96%), followed by pulmonary hypertension (78%). The common final modes of death were sudden cardiac or cardiopulmonary arrest (26%) and possible progressive pulmonary hypertension-related events (26%). These data of improved survival, through neonatal intensive treatment, are helpful for clinicians to offer the best information on treatment options to families of patients with trisomy 18.

Clinical characteristics and survival of trisomy 18 in a medical center in Taipei, 1988–2004

Trisomy 18 is the second most common autosomal trisomy in newborns. The birth prevalence of this disorder is approximately 1 in 3,000 to 1 in 8,000, and the life span of the majority of patients is less than 1 year. As information regarding outcome in trisomy 18 is rather fragmentary in the literature, this study is aimed at investigating the survival and natural history of trisomy 18. We also evaluated the survival age and management of trisomy 18 in two different periods, before and after the implementation of National Health Insurance (NHI) program. Thirty-nine cases of trisomy 18 were collected in Mackay Memorial Hospital in a 17-year period, from 1988 to 2004. Delivery data, survival age, management before and after the implementation of NHI program, structural defects, image findings and cytogenetic results were analyzed by medical and nurse's records. The diagnosis of trisomy 18 was based on the prenatal amniocentesis or postnatal chromosome analysis. Three patients had trisomy 18 mosaicism. Since cardiovascular and central nervous systems are the most common organ systems involved in this disorder, 31 patients received brain ultrasonography and heart ultrasonography for evaluation of their multiple anomalies after admission. All patients except one died in their first year due to severe malformations of the cardiovascular or central nervous systems. The median survival age was 6 days. We found a longer survival with female patients than with male patients (P < 0.05). Implementation of NHI program in the more recent decade of this study period was associated with longer survival of trisomy 18 (P < 0.05). The three most common structural defects were clenched hands (95%), rocker bottom feet (90%), and low set or malformed ears (90%). Low birth weight was present in 90%. By cardiac ultrasonography, the top four heart defects were ventricular septal defect (94%), patent ductus arteriosus (77%) and atrial septal defect (68%). However, ten cases (32%) had complex congenital heart defects. By brain ultrasonography, the most common brain lesion was cerebellar hypoplasia (32%), followed by brain edema (29%), enlarged cisterna magna (26%) and choroid plexus cysts (19%). Although most patients with trisomy 18 die within the first few weeks after birth, it is important to recognize that a small but notable percentage of these patients will survive the first year. When prenatal or postnatal decisions need to be made, the possibility of long-term survival should be included in any discussion to enable families to make the most appropriate decision.

Constitutional duplication 11q23 de novo involving the MLL gene

We report a child with mental retardation, brain anomalies and congenital heart defect. His karyotype, after G-banding and FISH with a whole chromosome probe for chromosome 11 and a locus-specific probe for the MLL gene, was 46,XY,dup(11)(q23q23).ish dup(11)(q23q23)(wcp11+, MLL++) de novo; i.e., he had a pure partial 11q23 duplication. Clinical and cytogenetic findings of the present case were compared with the 7 previously reported cases with pure partial trisomy 11q; in 6/8 cases the region 11q23 was involved. We conclude that the scarce number of cases and their heterogeneity do not allow to establish a reliable genotype-phenotype correlation.

A case of trisomy 12 mosaicism with pituitary malformation and polycystic ovary syndrome

We report the case of a patient (followed from birth to 15 years) presenting with trisomy 12 mosaicism, and focus on the endocrine phenotype associating a pituitary malformation and ovarian abnormalities. We describe the dysmorphic features and their evolution, the growth retardation and ovarian symptoms. Complete growth hormone deficiency was confirmed on auxological data, stimulation test and was related to pituitary stalk interruption, diagnosed by magnetic resonance imaging. Effect of growth hormone treatment was satisfactory resulting in a normal adult height. She also presented premature thelarche associated with right ovarian hypertrophy (4 to 5 fold the volume of the left ovary) which remained constant until 15 years of age. Diagnosis of trisomy 12 mosaicism was made on skin and ovarian karyotypes. The possible relation between these endocine findings and some genes located on chromosome 12 involved in pituitary and ovarian development is discussed.

Working memory in the Ts65Dn mouse, a model for Down syndrome

This study used a matching-to-position schedule of reinforcement to examine working memory in Ts65Dn and littermate control mice. Initially there appeared to be a memory deficit in the Ts65Dn mice, which disappeared with extended practice. Thus, what appeared as a memory deficit may actually be the result of a delay in learning the concept of matching. These results suggest that delayed learning may be an important factor in other procedures examining working memory in Ts65Dn mice and have important implications for clinical treatment of Down syndrome patients.

Cocaïne et trisomie 8 associées au diagnostic prénatal d’agénésie du corps calleux

We report the case of a newborn presenting an agenesis of corpus callosum (ACC) discovered in the prenatal period and initially related to cocaine exposure during the first trimester of gestation. The cytogenetic analysis revealed a trisomy 8 mosaicism. The putative role of prenatal cocaine exposure and mosaicism for chromosome 8 in ACC are discussed. This report emphasizes the specific analysis of chromosome 8 by using fluorescence in situ hybridization as a complement to routine cytogenetic analysis for prenatal diagnosis of ACC.

Abnormal synaptic plasticity in the Ts1Cje segmental trisomy 16 mouse model of Down syndrome

Due to the homology between human chromosome 21 and mouse chromosome 16, trisomy 16 mice are considered animal models of Down syndrome (DS). Abnormal hippocampal synaptic plasticity and behavior have been reported in the segmental trisomy 16 Ts65Dn mouse. In the Ts1Cje DS mouse model, which has a shorter triplicated chromosomal segment than Ts65Dn, more subtle hippocampal behavioral deficits have been reported. In this study, we investigated CA1 hippocampal synaptic plasticity, long-term potentiation (LTP) and depression (LTD) in the Ts1Cje mouse. Field excitatory postsynaptic potentials (fEPSPs) were recorded from the CA1 area of in vitro hippocampal slices from the Ts1Cje mouse and diploid controls, LTP was induced by a single tetanizing train pulse (1 s) at 100 Hz and LTD by a 900-pulse train at 1 Hz. We report for the first time that compared to diploid controls, the hippocampus from the Ts1Cje mouse had a smaller LTP and an increased LTD. The changes are less dramatic than had been reported previously for the Ts65Dn mouse. Furthermore, in the Ts1Cje mouse trains of pulses at both 20 Hz and 100 Hz produced a decrease in the evoked fEPSPs over the length of the train in comparison to diploid fEPSPs. These findings suggest that genes from Ts1Cje chromosome, including GIRK2 potassium channel, contribute to abnormal short- and long-term plasticity.

Trisomy of chromosome 16p13.3 due to an unbalanced insertional translocation into chromosome 22p13

A dysmorphic boy with severe mental retardation was found on array CGH to have an insertional translocation of chromosome 16p13.3 into the short arm of chromosome 22, karyotype 46,XY,.ish der(22),ins(22;16)(p13;p13.3p13.3) de novo. His clinical features overlap with the reported cases of 'duplication 16p' syndrome, namely a round face, hypertelorism, a long philtrum, micrognathia, a thin upper lip, a posterior cleft palate and low set, simple ears, clubbed feet, severe developmental delay, psychomotor retardation and seizures. This 4-year boy with trisomy 16p13.3 has the smallest duplication reported of this critical region, which could not be detected without array CGH. The maximal duplicated region is gene rich and contains about 80 genes and/or candidate genes. Assignment of the genes that contribute to the observed phenotype awaits the characterisation of other patients with small duplications in this region.

Identification of an unbalanced X-autosome translocation by array CGH in a boy with a syndromic form of chondrodysplasia punctata brachytelephalangic type

Screening of a large series of patients with unexplained mental retardation with a 1 Mb BAC array resulted in the detection of several cryptic chromosomal imbalances. In this paper we present the findings of array CGH screening in a 14-year-old boy with the brachytelephalangic type of chondrodysplasia punctata, mental retardation and obesity. On several occasions, cytogenetic analysis of this boy revealed a normal karyotype. Subsequent screening with array CGH resulted in the detection of a distal 9p trisomy and distal Xp nullisomy caused by an unbalanced X;9 translocation: 46,Y,der(X)t(X;9)(p22.32;p23). The identification of this de novo chromosomal rearrangement not only made accurate genetic counselling possible but also explained most of the phenotypic abnormalities observed in this patient. This study confirms the power of array CGH in the detection of subtle or submicroscopic chromosomal changes.

Costovertebral dysplasia in a patient with partial trisomy 22

A newborn female presented with costovertebral dysplasia (CVD), subtle facial anomalies, and neonatal respiratory distress. Her karyotype demonstrated a small supernumerary NOR-positive marker that was subsequently identified as del(22)(q11.2). This extra structurally abnormal chromosome was found by DNA microsatellite marker analyses to be derived from a paternal chromosome 22. The child has had severe growth and developmental delay along with pulmonary insufficiency and hypoxia but is presently stable at age 20 months. Findings in our patient correlate with similar observations in children with small markers derived from D/G and D/D translocations reported before banding technology was available. These reports and recent mapping results suggest that a pericentric gene family, distributed on one or more acrocentric chromosomes, may have played a role in the development of the human axial skeleton. Data from additional studies will be needed to confirm or refute this hypothesis.

Restoration of DSCR1 to disomy in the trisomy 16 mouse model of Down syndrome does not correct cardiac or craniofacial development anomalies

The Down syndrome critical region 1 (DSCR1) gene is located in syntenic regions of human chromosome 21 and mouse chromosome 16 and encodes a regulatory protein in the calcineurin/NFAT pathway. DSCR1 expression in the embryonic brain, craniofacial structures, and heart is consistent with a role in contributing to Down syndrome developmental anomalies. In the trisomy 16 (Ts16) murine model of Down syndrome, expression of DSCR1 isoforms is elevated and NFAT transcriptional activity is decreased in the developing heart and brain. The individual contribution of DSCR1 to Down syndrome-related anomalies was examined by specific restoration of DSCR1 to disomic levels in Ts16 embryos. However, genetic restoration of DSCR1 did not rescue major morphological abnormalities in cardiac or craniofacial development. These data demonstrate that trisomy of DSCR1 alone does not significantly contribute to developmental defects in Ts16 mice and underscore the complexity of developmental anomalies associated with Down syndrome.

[The significance of screening tests for aneuploidies in populations at low and high maternal-age-related risk]

AIM

The aim of this study was to evaluate the validity of the triple test and the screen test in maternal populations at low and high maternal-age-related risk for fetal aneuploidy.

METHODS

As a whole, 9,680 pregnant women at low risk and 627 at high risk underwent the triple test; 2,780 pregnant women at low risk and 408 at high risk underwent the screen or combined test; sensitivity, specificity, false positives and detection rate were compared between populations using Student's t-test.

RESULTS

The triple test showed a detection rate of 75% in the low and 83.3% in the high risk population with a difference (P<0.003) for detection of trisomies 21 and 18 between the 2 populations; the screen test had a detection rates of 100% and 90% in the 2 populations, respectively, with a difference (P<0.005) between the 2 tests.

CONCLUSIONS

Both tests are reliable for screening aneuploidies in the low risk population, the screen test having better performance; in the high risk population, the number of invasive procedures can be reduced by 78% with the triple test and by 84% with the screen test.

Nephroblastomatosis and loss of WT1 expression associated with trisomy 13

Trisomy 13 (Patau's syndrome) is a rare finding in newborns. The life span of babies affected by this chromosome abnormality is severely shortened, and multiple, partly severe malformations occur. In this study, we report on an unborn with trisomy 13 (artificially aborted on the 24th week) which showed, among other typical deformities, bilateral nephrogenic rests (nephroblastomatosis). Using molecular analysis, a loss of Wilms' tumor gene 1 (WT1) transcript and a biallelic expression of insulin growth factor 2 (IGF2) could be revealed. To our knowledge, this is the first reported case of trisomy 13 which showed this type of anomaly and gene expression findings.

Delineation of a supernumerary marker chromosome utilizing a multimodal approach of G-banding, fluorescent in situ hybridization, confirmatory P1 artificial chromosome fluorescent in situ hybridization, and high-resolution comparative genomic hybridization

We describe the structure of a supernumerary marker in a child who presented with a right atretic ear and multiple congenital anomalies. Using G-banding, fluorescent in situ hybridization (FISH), P1 artificial chromosome FISH and high-resolution comparative genomic hybridization (CGH), the marker was demonstrated to be a derivative chromosome resulting from malsegregation of a paternal 8;22 translocation: 47,XY, +der(22)t(8;22)(q24.1; q11.2). This case is noteworthy because the marker, while sharing similarities to der(22) in the Cat Eye syndrome (CES), also contains chromosome 8q material. This partial 8q trisomy confounds the diagnosis of CES associated with pure trisomy or pure tetrasomy 22q. The paternal translocation is noted with prolonged infertility and oligospermia, which again highlights the utility and necessity of chromosome analysis in this setting.

Prenatal diagnosis of trisomy 6 mosaicism

We report on a fetus with multiple congenital anomalies detected at the prenatal ultrasound examination and a trisomy 6 mosaicism in the amniocytes. The pregnancy was interrupted in the 18th gestational week and the autopsy revealed malformations including cleft right hand, arthrogryposis and hypoplasia of the 4th digit of the left hand, syndactylies and overlapping toes, facial dysmorphism with hypertelorism and low-set ears, ventricular septum defect (VSD), intestinal malrotation and scoliosis. Trisomy 6 mosaicism was detected in cultured amniocytes (13.3%), confirmed in umbilical cord fibroblasts (40%) and by fluorescence in situ hybridization on other fetal tissues. Trisomy 6 mosaicism is a very rare finding with only eight cases previously reported to our best knowledge.

Polymerase chain reaction method to identify Down syndrome model segmentally trisomic mice

The Ts65Dn segmentally trisomic mouse possesses an extra copy of a segment of chromosome 16 translocated to chromosome 17. This segment includes the mouse homolog of the Down syndrome critical region of human chromosome 21. The Ts65Dn mouse serves as a useful model to study the developmental regulation of the Down syndrome phenotype. To identify mice bearing the extra chromosome 16 segment, we developed a polymerase chain reaction (PCR) method as an alternative to karyotyping. Conditions under which segments of genes on chromosome 16 (App and Dyrk1a) could be coamplified with a control gene on chromosome 8 (Acta1) so that the yield of each PCR product was proportional to the amount of its template were determined. The amplification products were resolved and quantified by two methods. In the first method, the DNA segments were separated by agarose gel electrophoresis and stained with ethidium bromide. The fluorescence yields were quantified by photodensitometry. In the second method, the fragments were resolved and quantified by the high-performance DNA analysis system, a high-throughput, multichannel, microcapillary electrophoresis instrument. The results of both methods were within 10% of the expected ratio of 1.5. Application of these methods has allowed the maintenance of a Ts65Dn breeding colony through six generations and should permit the precise and efficient identification of trisomic and disomic animals at any developmental stage with minimally invasive procedures.

Myelodysplastic syndrome associated with trisomy 2

Clinical course and cytogenetic analysis suggest that myelodysplasia (MDS) is one step in a multistep model of malignant transformation of haematopoietic stem cells to acute myeloid leukaemia (AML). We report a further case of MDS associated with trisomy 2, and comment on the significance of the cytogenetic abnormality, which as a sole abnormality only occurs in MDS, but is found in combination with other chromosomal abnormalities in AML. Previous reports on balanced and unbalanced chromosomal abnormalities associated with therapy related MDS and therapy related AML suggest that trisomy 2 is an early chromosomal abnormality in leukaemogenesis.

Left ventricular noncompaction cardiomyopathy in association with trisomy 13

In recent years, left ventricular noncompaction (LVNC) has been recognized as a distinct form of cardiomyopathy with its own clinical presentation and natural history. More than 100 cases of LVNC have been described in children. Although LVNC has been described in association with metabolic disorders such as Fabry's disease or genetic disorders such as Roifman's syndrome, this case represents the first report of LVNC in a child with trisomy 13.

Immunophenotypic and genetic characterization of a CD8 positive Mantle Cell Lymphoma in a patient with concomitant Mycosis Fungoides

Mantle cell lymphoma (MCL) is immunophenotypically characterized by cell surface co-expression of CD19, CD20, CD5, IgM and FMC7. However, the concomitant presence of other antigens distinctive of a particular leukocyte subset, e.g. T-lymphocytes, is an exceptional finding in MCL. Here, the first case of a blastic MCL in leukaemic phase with aberrant expression of the T-cell associated antigen CD8 occurring in a patient with concomitant Mycosis fungoides is described. Comprehensive immunophenotypic analysis showed that the MCL cells expressed the typical B-lymphocytic markers, were CD5 and CD8 positive, but did not express other T-cell proteins, such as CD2, CD3, CD4, CD7, TCRalphabeta and TCRgammadelta. The MCL cells expressed both CD8alpha and CD8beta chains indicating cell surface presence of CD8alphabeta heterodimers. Intriguingly, expression of the cytotoxic enzymes perforin and granzyme A was detected by RT-PCR. Cytogenetic and molecular genetic analysis of the lymphoma cells confirmed cyclin D1 overexpression secondary to the t(11;14)(q13;32) chromosomal translocation. Furthermore, trisomy 11, trisomy 14 and extra copies of t(11;14) translocated chromosomes were detected in sub clones of the analyzed MCL cells. Clinically, an aggressive course of disease including cerebral lymphoma involvement was noted in the reported patient. Hence, systematic studies addressing the incidence, biology and clinical behavior of this form of MCL seem to be justified in future.

Trisomy 20 mosaicism caused by a maternal meiosis II error is associated with normal intellect but multiple congenital anomalies

Mosaicism for trisomy 20 is generally ascertained following prenatal sampling and rarely is associated with significant phenotypic abnormalities. Uniparental disomy for chromosome 20 in the euploid lines has been found in several cases, which showed relatively mild clinical features, primarily growth delay. Here we report on a case of mosaic trisomy 20 in a child with normal neurologic development who was ascertained because of multiple physical anomalies including spinal segmentation anomalies and altered skin pigmentation. Trisomic cells were found in buccal epithelial cells and in cultured skin fibroblasts but not in peripheral blood. Molecular analysis of blood cells, fibroblasts, and parental cells gave evidence of a maternal meiosis II error as the cause of the trisomy. Disomic cells presumably arose through trisomy rescue, and no evidence was found for uniparental disomy in these cells.

Decreased cholesterol synthesis as a possible aetiological factor in malformations of trisomy 18

We report a series of neonates and foetuses with trisomy 18 and abnormally low cholesterol levels and propose that down regulation of cholesterol synthesis in trisomy 18 is, in part, responsible for its phenotype. Cholesterol is a major structural lipid of cell membranes, as well as the precursor of steroid hormones and bile acids. Several human malformation syndromes have been identified biochemically as disorders of cholesterol biosynthesis. Trisomy 18, a multi-system malformation syndrome, has clinical features that overlap with those of disorders of cholesterol biosynthesis and dysregulation of this pathway may have a role in the developmental pathology.