China
Africa
Explore chapters and articles related to this topic
Prenatal Diagnosis and Screening for Aneuploidy
Published in Vincenzo Berghella, Obstetric Evidence Based Guidelines, 2022
Sarah Harris, Angie Jelin, Neeta Vora
Physical characteristics that are not structural anomalies but occur more commonly in fetuses with trisomy 21 are called markers. By comparing the prevalence of markers in trisomy 21 fetuses to their prevalence in the normal population, a likelihood ratio (LR) can be calculated, which can be used to modify risk. This is the basis for ultrasound screening for trisomy 21. In order for a marker to be useful for trisomy 21 screening, it should be sensitive (i.e. present in a high proportion of trisomy 21 pregnancies), specific (i.e. not commonly seen in normal fetuses), easily imaged in standard sonographic examination, and present early enough in the second trimester that diagnostic testing can be performed so that results are available when pregnancy termination remains an option. A list of markers and likelihood ratios are seen in Tables 5.4 and 5.5, respectively [33–35]. Markers commonly sought to assess the risk of trisomy 21 are discussed in the following sections.
The Genetic Risk of a Couple Aiming to Conceive
Published in Carlos Simón, Carmen Rubio, Handbook of Genetic Diagnostic Technologies in Reproductive Medicine, 2022
Joe Leigh Simpson, Svetlana Rechitsky, Anver Kuliev
Secondary prevention is standard obstetrical practice. Interrogation of an established pregnancy traditionally follows an invasive prenatal diagnostic procedure (amniocentesis or chorionic villus sampling, CVS). Chromosomal abnormalities exist in 1 in 200 liveborn infants. Attracting the greatest clinical attention are the three autosomal trisomies compatible with livebirth (7–9). All are associated with advanced maternal age (10–12), and usually arise during maternal meiosis I. Liveborn risk for trisomy 21 at maternal age 35 years is 0.30% (3/1000). The prevalence at mid-trimester (assessed by amniocentesis) is 0.33%, whereas prevalence in the first trimester (assessed by CVS) is 0.39% (11). Higher rates earlier in gestation reflect ongoing natural selection against aneuploid embryos and fetuses (12).
Answers
Published in Samar Razaq, Difficult Cases in Primary Care, 2021
Abnormal development of the third and fourth pharyngeal arches during embryonic development results in DiGeorge’s syndrome. The majority of cases are caused by chromosomal deletion at 22q11, although other chromosomal abnormalities have also been implicated. It results in immunodeficiency (due to inadequate thymic development), congenital heart defects, hypocalcaemia (due to underactive parathyroids) and abnormal facies. An extra copy of chromosome 18 results in Edwards’s syndrome, in which there may be a wide variety of congenital defects and mental retardation. Trisomy 21 is commonly known as Down’s syndrome.
Transient abnormal myelopoiesis in Down syndrome: Experience of long term follow up from a single tertiary center in Thailand
Published in Pediatric Hematology and Oncology, 2023
Thirachit Chotsampancharoen, Shevachut Chavananon, Pornpun Sripornsawan, Natsaruth Songthawee, Edward B. McNeil
Over the 26-year study period, we identified 32 patients diagnosed as DS with TAM from 997 DS patients, giving an incidence of TAM of 3.2%. Among these, the median age was 5 days (range: 1-50 days), with a male:female ratio of 0.78:1. The median gestational age was 38 weeks (range: 33 to 40 weeks). Thirty of the 32 patients (93.8%) had Down syndrome features with chromosome studies showing trisomy 21. Two of the 32 patients (6.2%) had normal phenotypes but chromosome studies showed mosaicism patterns of 47,XX,+21/46,XX and 47,XY,+21/46,XY. Hepatomegaly (93.8%), splenomegaly (78.1%), respiratory distress needing oxygen therapy (62.5%), and jaundice (40.6%) were the most common physical findings in the symptomatic patients. The clinical manifestations of the patients at presentation are shown in Table 1.
Assessment of foetal ventriculomegaly from prenatal to early postnatal period: a single-centre retrospective cohort study
Published in Journal of Obstetrics and Gynaecology, 2022
Nurullah Cihan Sohret, Ayse Neslihan Tekin, Ozge Surmeli Onay, Kamuran Suman, Ozge Aydemir, Melih Velipasaoglu
Other than infections, probability of chromosomal anomalies should be kept in mind in foetal VM cases. Graham et al. (2001) found aneuploidy in 14.2% of mild and moderate VM cases and 17.4% in severe VM. Similarly, Gezer et al. (2014) in their study with 140 VM cases detected chromosomal anomalies in seven. Regarding the genetic diagnosis of foetal VM cases, a study including 231 isolated VM cases in China found that the most common chromosomal anomaly was Trisomy 21 followed by 45 + X (Turner Syndrome; Zhao et al. 2018). In our study group, Trisomy 21 was detected in two cases and Trisomy 18 in one case. In the case of Trisomy 18, pericardial and pleural effusions, coroid plexus cysts, and a single umbilical artery in the cord were detected. One of the Trisomy 21 cases had no other signs; while the other exhibited pelvicaliectasis and an intracardiac hyperechogenic focus in the left ventricule. In all three cases with chromosomal abnormalities, the VM was mild.
Co-occurrence of incontinentia pigmenti and down syndrome: examining patients’ potential susceptibility to autoimmune disease, autoinflammatory disease, cancer, and significant ocular disease
Published in Ophthalmic Genetics, 2021
David C. Gibson, Natario L. Couser, Kayla B. King
Down syndrome is a common genetic condition that occurs at an incidence of about one case in every 700 births. Most commonly, it is caused by a nondisjunction event resulting in the presence of three copies of chromosome 21, otherwise known as trisomy 21. A minority of cases are caused by a Robertsonian translocation which results in the presence of extra material from chromosome 21 attached to another chromosome. Down syndrome classically presents with characteristic physical and facial features, in addition to developmental and intellectual delays. Like patients with Noonan syndrome, individuals with Down syndrome have an increased risk of developing autoimmune and autoinflammatory diseases, like hypothyroidism, type 1 DM, celiac disease, and arthropathy of Down syndrome. Individuals with Down syndrome also have a predisposition to certain cancers, like acute myelocytic leukemia (AML), acute lymphocytic leukemia (ALL), and testicular malignancy. The susceptibility to immune-related disorders and certain cancers seen in patients with Down syndrome is thought to be due to interferon hyperactivity and disorganized T cell and B cell responses.