Turner syndrome: New insights from prenatal genomics and transcriptomics

In some parts of the world, prenatal screening using analysis of circulating cell‐free (cf) DNA in the plasma of pregnant women has become part of routine prenatal care with limited professional guidelines and without significant input from the Turner syndrome community. In contrast to the very high positive predictive values (PPVs) achieved with cfDNA analysis for trisomy 21 (91% for high‐risk and 82% for low‐risk cases), the PPVs for monosomy X are much lower (~26%). This is because the maternal plasma sample contains both maternal cfDNA and placental DNA, which is a proxy for the fetal genome. Underlying biological mechanisms for false positive monosomy X screening results include confined placental mosaicism, co‐twin demise, and maternal mosaicism. Somatic loss of a single X chromosome in the mother is a natural phenomenon that occurs with aging; this could explain many of the false positive cfDNA results. There is also increased awareness of women who have constitutional mosaicism for 45, X who are fertile. It is important to recognize that a positive cfDNA screen for 45, X does not mean that the fetus has Turner syndrome. A follow‐up diagnostic test, either amniocentesis or neonatal karyotype/chromosome microarray, is recommended. Research studies on cell‐free mRNA in second trimester amniotic fluid, which is almost exclusively fetal, demonstrate consistent dysregulation of genes involved in the hematologic, immune, and neurologic systems. This suggests that some of the pathophysiology of Turner syndrome occurs early in fetal life and presents novel opportunities for consideration of antenatal treatments.     

Expanding non‐invasive prenatal testing beyond chromosomes 21, 18, 13, X and Y

Non‐invasive prenatal testing (NIPT) based on cell‐free DNA in maternal plasma is being expanded to include additional chromosome abnormalities beyond those involving chromosomes 21, 18, 13, X and Y. Review of population cytogenetic data provides insight into the likely number of additional abnormalities detectable. Additional clinically significant and cytogenetically recognizable abnormalities are present in less than 0.1% of newborns but clinically significant, or potentially significant, sub‐microscopic imbalances are expected to be present in 1.7%. Cytogenetic studies on chorionic villus samples suggests that after excluding abnormalities involving chromosomes 21, 18, 13, X and Y, approximately 0.6% of NIPT results may be positive for an unbalanced abnormality attributable to mosaicism but most of these will not be confirmed at amniocentesis or in newborns. NIPT has also been developed for specific microdeletion syndromes and initial experience is now available. Laboratory procedures such as deeper sequencing and additional data analytics are rapidly evolving but even with existing protocols, it is already clear that NIPT does not necessarily need to be limited to trisomies 21, 18, 13 and the sex‐chromosome abnormalities. Patient educational materials and genetic counseling services need to be available for women offered expanded NIPT.     

“It's about having the choice”: Stakeholder perceptions of population‐based genetic carrier screening for fragile X syndrome

This project explored, the views of key stakeholders regarding population‐based genetic carrier screening for fragile X syndrome (FXS). Interviews and focus groups were conducted with healthcare providers, relatives of individuals with FXS and members of the general population. Data were transcribed verbatim and coded into themes. 188 individuals took part in this study. Perceived benefits of carrier screening included: learning the risk of having a child with FXS; learning the risk of fragile X‐associated primary ovarian insufficiency; and the opportunity for carriers to access reproductive options. Concerns included: the emotional impact of screening and receiving a carrier result; the predictive testing nature of the carrier test with respect to fragile X‐associated tremor/ataxia syndrome; potential confusion created by receiving an intermediate result; and implications of genetic screening for society. Overall, population‐based genetic carrier screening was perceived to be acceptable provided it is optional and offered at an appropriate stage of life. With the support of the participants to promote individual choice by offering a population‐based carrier screening program for FXS, it is essential to carefully consider how screening might be offered in order to ensure broad accessibility and facilitation of decision‐making. © 2012 Wiley Periodicals, Inc.     

A 15‐year‐long Southern blotting analysis of FMR1 to detect female carriers and for prenatal diagnosis of fragile X syndrome in Taiwan

Here, we review the results of Southern blotting analyses of the FMR1 gene performed in our reference laboratory in Taiwan over a 15‐year period. In total, 725 high‐risk women with a family history of fragile X syndrome (FXS) or idiopathic intellectual disability, 3911 low‐risk pregnant women without such family history, and prenatal diagnosis data for 32 foetuses from 24 carrier mothers were included. Only 2 carriers were in the low‐risk group, which indicated a prevalence of 1 of 1955 women (95% confidence interval: 1/7156‐1/539). A total of 100 carriers were found to be in the high‐risk group, thus revealing a significantly higher frequency than the low‐risk group (100/725 vs 2/3911, P<0.0001). Eight of the 14 foetuses that inherited the maternal mutant allele were verified to have a full mutation, with the smallest maternal pre‐mutation allele carrying 56 CGG repeats. The overall findings confirmed that the carrier prevalence among low‐risk women in Taiwan is significantly lower than that reported in western countries. Therefore, the most important step for preventing FXS in Taiwan would be to focus on high‐risk women by promoting general awareness of this disease and spreading knowledge regarding the benefits of carrier screening and prenatal testing.     

Clinical and molecular cytogenetic observations in three cases of “trisomy 12p syndrome”

Two unpublished cases with partial tandem duplication of 12p and one previously published case were studied by fluorescence in situ hybridization using 11 cosmid DNA probes from 12p. We propose that the smallest duplications of 12(p13.2pter) and 12(p13.1p13.33) produce the “trisomy 12p syndrome” which is characterized by heavy birth weight, macrocephaly, muscular hypotonia, short neck, flat face, high forehead, prominent cheeks, large philtrum, short nose with anteverted nostrils, and broad everted lower lip. From a review of the published cases we conclude that gross malformations are lacking in “pure” trisomy 12p, and mental retardation is severe in complete and moderate in partial trisomy 12p. Polydactyly and accessory nipples were found only with almost complete trisomy 12p. Abnormalities of hair growth may be related to a gene at 12p. The sub-band 12p11.21 may be critical for acrocallosal syndrome. Macrocephaly may be due to a metabolic disorder. © 1996 Wiley-Liss, Inc.     

Non‐invasive prenatal diagnosis for single gene disorders: experience of patients

The aim of this study is to explore women's experiences of using newly developed non‐invasive prenatal diagnosis (NIPD) for single gene disorders. Methods used in this study include qualitative one‐to‐one interviews with eight women with pregnancies at risk of achondroplasia, Apert syndrome, thanatophoric dysplasia or a neuromuscular condition. The results of the study show that the women were positive about an accurate, safe, and early test. Where the foetus was at increased risk of inheriting a genetic condition, the benefits of NIPD over invasive testing were that it reduced the period of uncertainty and worry by being conducted within the first trimester. For those women for whom there was a low recurrence risk, the period of uncertainty could be reduced and pregnancy ‘normalized’ earlier. For women who would not have risked invasive testing, NIPD enabled them to have an early diagnostic test that was more accurate than ultrasound. Where ultrasound abnormalities were detected, NIPD ended the ‘diagnostic odyssey’, enabling women to make practical and psychological preparations for the birth. NIPD conducted through specialist services was considered most appropriate. NIPD for these particular single gene disorders was appreciated by women and appears to be satisfactory. Further exploration of stakeholder views may be required to inform more widespread implementation of NIPD for a broader range of genetic conditions.     

“I'm not a patient,I'm a person”: The Experiences of Individuals With Intellectual Disabilities and Challenging Behavior—A Thematic Synthesis of Qualitative Studies

Individuals with intellectual disabilities (ID) and challenging behavior often have complex care needs and may be reliant on care support services. This thematic synthesis examines published qualitative research on the experiences of individuals with ID in relation to received service supports and interventions. Seventeen studies met criteria. Four themes emerged: (1) Imbalance of power, (2) Causal attributions about challenging behavior, (3) Experiences of restrictive interventions, and (4) Opportunities for improvement: proactive interventions. The accumulative stressors of living in a residential placement were regarded as a cause of continued challenging behaviors. The impersonal attitude of support staff was regarded as a major contributory factor. The findings can inform service providers about how best to support individuals with ID and challenging behavior.     

Clinical implementation of NIPT – technical and biological challenges

Non‐invasive prenatal testing (NIPT) for fetal aneuploidy detection is increasingly being offered in the clinical setting. Whereas the majority of tests only report fetal trisomies 21, 18 and 13, genome‐wide analyses have the potential to detect other fetal, as well as maternal, aneuploidies. In this review, we discuss the technical and clinical advantages and challenges associated with genome‐wide cell‐free fetal DNA profiling.     

“Cannonballs” and psammoma bodies: Unusual cytologic features of metastatic pulmonary small‐cell carcinoma in a pleural effusion

Large three‐dimensional cell aggregates and psammoma bodies are usually encountered in benign serous effusions (mesothelial hyperplasia and endosalpingiosis), mesotheliomas, and metastatic papillary carcinomas. We report a case of pulmonary small‐cell carcinoma occurring in an 88‐year‐old woman that initially presented with a malignant pleural effusion characterized cytologically by a predominance of large three‐dimensional neoplastic cell aggregates (“cannonballs”), associated with rare psammoma bodies. Although the crowded three‐dimensional tumor‐cell aggregates did not allow detailed cytologic examination, the diagnosis of metastatic small‐cell carcinoma could be established noting the characteristic chromatin features of the occasional single neoplastic cells and the characteristic “cell‐in‐cell” and “stack‐of‐coins” arrangements of rare small clusters of neoplastic cells. Immunoperoxidase stains showing positivity of the tumor cells for CD56, synaptophysin, and TTF1 further supported this diagnosis. Endobronchial ultrasound‐guided fine‐needle aspiration of a mediastinal lymph node subsequently confirmed the diagnosis of pulmonary small‐cell carcinoma. Metastatic pulmonary small‐cell carcinoma should be considered in the differential diagnosis of serous effusions showing large three‐dimensional neoplastic cell aggregates and psammoma bodies to prevent a potential diagnostic pitfall. Diagn. Cytopathol. 2013. © 2011 Wiley Periodicals, Inc.     

“Anemone” Cell (Villiform) Tumors: Electron Microscopy and Immunohistochemistry of Five Cases

The authors are grateful to Gilbert C. Fischer, MD, Mona Ghobrial, MD, John C. Merenkov, MD, and Balbino B. Fernandez, MD for their contributions of case material to this study and to Hector Battifora, MD for performing the monoclonal anti-keratin antibody stains.

Five large cell malignant neoplasms were studied by immunohistochemistry and electron microscopy. Ultrastructural examination demonstrated numerous circumferential microvilli in 3 cases and a more polarized distribution in 2 cases. The tumor cells in 2 cases demonstrated the surface glycoprotein T29/33, indicative of a hematopoietic neoplasm. Two cases (including one positive for T29/33) contained intracytoplas-mic IgG-kappa. Anti-keratin staining using both polyclonal and monoclonal antibodies was negative. Two patients are alive and in remission after treatment for lymphoma. One died with tumor following a progressive course, and one has been lost to follow-up. A fifth patient died of tumor and at autopsy was found to have a disseminated pancreatic tumor. Microvilli around large malignant cells have been commonly associated with epithelial tumors; however, our findings indicate that, in the absence of intercellular junctions and tonofilaments, the possibility of malignant lymphoma should be considered and pursued immunohistochemically.     

Polymerase chain reaction-directed DNA sequencing of bleomycin-induced “nondeletion”-Type, 6-thioguanine-resistant mutants in chinese hamster ovary cell derivative AS52: Effects of an inhibitor and a mimic of superoxide dismutase

Bleomycin-induced, 6-thioguanine-resistant, “non deletion” mutants pretreated with or without either TRIEN (triethylenetetramine), a superoxide dismutase (SOD) inhibitor, or TEMPOL (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl), a SOD mimic, were analyzed by polymerase chain reaction (PCR)-directed DNA sequencing in a Chinese hamster ovary (CHO) cell derivative, AS52. Among the 23 bleomycin-induced mutants, six have 3-bp 5′-TGA-3′ deletions in the region of 366-371, five have single-base deletions, seven have base substitutions, three have insertions, and two have possible translocations. Among the 16 bleomycin-induced mutants pretreated with TRIEN, six have the 5′-TGA-3′ deletion (366-371), two have single-base deletions, one has a 13-bp deletion, four have single-base substitutions, one has a double-base substitution, and two have insertions. Among the 17 bleomycin-induced mutants pretreated with TEMPOL, six have the same TGA deletions, two have single-base deletions, two have single-base insertions, four have single-base substitutions, one mutant has a 12-bp deletion, one has a 13-bp deletion, and one mutant shows no detectable change in its coding region in the DNA sequence. A possible shift from a ROS-mediated mutational spectrum to a spontaneous mutational spectrum by TRIEN further indicates that reactive oxygen species play an important role in bleomycin mutagenesis in mammalian cells. © 1994 Wiley-Liss, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.