Trisomy 18 — Edwards syndrome

March 18, Trisomy 18 Awareness Day

Trisomy 18 is the second most common and second most severe trisomy1. The condition arises if the egg or the sperm carries an extra chromosome 18, that when combined passes 3 copies of chromosome 18 instead of 2 to the developing baby. Trisomy 18 was first described in 1960 by two groups; John Edwards, whom the disease is named after, and by Smith, Patau, Therman and Inhorn – the team that also described Trisomy 13, Patau syndrome2,3.

Globally, the condition occurs in approximately 1 in 5,000 live births4. The prevalence is greater, estimated to be around 1 in 2,500, but fetal loss during pregnancy and selective terminations after diagnosis due to the severity of the condition are high1,5. Maternal age plays a factor in trisomy 18, and with the mean maternal age having increased during the last 20 years, prevalence rates of trisomy 18 have risen5.

Trisomy 18 is considered less severe than trisomy 13, but the mortality rates are still high with many stillbirths and miscarriages during the first pregnancy months. The chance of spontaneous fetal loss rises from 28% to 41% from weeks 12 to 205. Survival after birth is challenging, with 50% of children sadly dying within their first week of life1,6. Individual symptoms can vary greatly in severity and complexity as 95% of the patients have full trisomy 18. Others have a mosaic form (some cells are trisomic for chromosome 18 and others carry the normal amount) or a partial form (only a section of chromosome 18 is extra)1,6. The latter form arises mostly when the parents unknowingly have a translocation (structural rearrangement of chromosomes) concerning chromosome 187. The risk of recurrence is around 1%, and it primarily applies to translocation carriers. Mosaic and partial forms of trisomy 18 are the ones with the best chances of survival. Patients having these forms are the small percentage that may survive well into adulthood, although with significant developmental and physiological delays. Interestingly, girls with trisomy 18 are found to respond better to treatment and survive longer than boys with trisomy 186,7.

Trisomy 18 is characterized by major and minor abnormalities, affecting all organs and systems. 90% of patients have heart defects, with bone abnormalities, kidney, respiratory, and intestinal problems, resulting in feeding difficulties, also being common4,6,8. Severe developmental delays, delayed growth and distinct characteristics like small jaw, low-set ears, clenched fists, strawberry-shaped head and rocker bottom feet (resembling a rocking chair) may also exist4,6,8. Failure to thrive (gain weight) is seen from the prenatal period, with fetuses affected being smaller than average, and with the mean birth weight being 1700-1800gr4,8.

No specific treatment is available for trisomy 18. Care for trisomy 18 children is usually palliative and conservative, depending on the severity of the symptoms, the parents’ wishes and the doctors’ medical judgement. Respiratory insufficiency and apnea are the major causes of death due to the breathing and feeding problems the patients experience8. Sadly, only around 10% of children with trisomy 18 pass their first birthday, and continuous support and health supervision is needed throughout their lives4,9.

Prenatal detection of trisomy 18 can be achieved through 1st and 2nd trimester screening, and routine ultrasounds as the presence of one or multiple findings are evident. These can include omphalocele (the baby’s organs are outside of the belly, covered in a sac), excess amniotic fluid, very little fetal activity and lower maternal hormone levels. A positive screening test should always be confirmed by a diagnostic test, like chorionic villus sampling (CVS) or amniocentesis. Combined prenatal screening for trisomy 18 is at least 78% accurate10. Non-Invasive Prenatal Testing (NIPT), analyzing the fetal blood through a blood sample taken from the expecting mother from the 10th week of pregnancy, is the most sensitive detecting method, with over 97% accuracy11. Thus, NIPT can reduce the number of unnecessary invasive procedures, and give parents invaluable time to think and research their options regarding clinical management and care.

Several support groups for families with children with trisomy 18 exist, providing precious emotional support and information by sharing experiences, health problems and advances in research. Trisomy 18 is a life-threatening condition, but it is not ‘universally lethal’. Spreading awareness about the condition, the different forms and the variability of symptoms is useful for expecting parents to receive an accurate image of trisomy 18 and be able to make their own informed decisions.

NIPT results, possible next steps and clinical management should always be fully discussed with your healthcare provider. VERACITY and VERAgene both detect Trisomy 18, amongst other common genetic disorders, from the 10th week of pregnancy. To learn more please visit www.nipd.com

For more information on support groups for trisomy 18, please visit http://www.chromosome18eur.org or http://www.soft.org.uk.

References:

  1. Trisomy 18 Foundation (2019) https://www.trisomy18.org/
  2. Edwards JH et al. (1960) ‘A new trisomic syndrome’. Lancet; April 9;1(7128): 787-790.
  3. Smith DW et al. (1960) ‘A new autosomal trisomy syndrome: multiple congenital anomalies caused by an extra chromosome’. The Journal of Pediatrics; Sep; 57:338-345.
  4. Genetics Home Reference (2019) https://ghr.nlm.nih.gov/condition/trisomy-18#genes
  5. Morris JK et al. (2008) ‘The risk of fetal loss following a prenatal diagnosis of trisomy 13 or trisomy 18’. American Journal of Medical Genetics; 146A:827–832.
  6. MSD Manuals Professional Version (2019) https://www.msdmanuals.com/professional/pediatrics/chromosome-and-gene-anomalies/trisomy-18
  7. Rasmussen SA et al. (2003) ‘Population-based analyses of mortality in trisomy 13 and trisomy 18’. Pediatrics; 111:777–784.
  8. Cereda A. and Carey JC. (2012) ‘The trisomy 18 syndrome’. Orphanet Journal of Rare Diseases; 7:81
  9. The chromosome 18 Registry & Research Society (2018) https://www.chromosome18.org/
  10. Breathnach FM et al. (2007) ‘First, second trimester evaluation of risk (FASTER) research consortium: first- and second-trimester screening: detection of aneuploidies other than down syndrome.’ Obstetrics and Gynecology; 110:651–657.
  11. Mackie FL et al. (2017) ‘The accuracy of cell-free fetal DNA-based non-invasive prenatal testing in singleton pregnancies: a systematic review and bivariate meta-analysis’. BJOG, 2017;124:32-46.


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NIPD Genetics - Privacy Policy

General Statement

NIPD Genetics is a leading, innovative biotechnology company that designs, develops, and provides a broad spectrum of healthcare services to its customers through its expansive portfolio of molecular and clinical laboratory tests in all disciplines.

At NIPD Genetics we are committed to protecting and respecting our customer’s privacy and personal information. Personal information or personal data means any information that identifies, relates to, describes, is capable of being associated with, or could be reasonably linked, directly or indirectly, with a particular individual, such as name, identification number, location data, an online identifier or to one or more factors specific to the physical, physiological, genetic, mental, economic, cultural or social identity of that individual.

NIPD Genetics collects and processes your personal information according to the General Data Protection Regulation (EU) 2016/679 and the Cypriot law providing for the protection of natural persons with regards to the processing of personal data and for the free movement of such data (L. 125(I)/2018). The following principles lie at the heart of our approach to handling personal data:

NIPD Genetics has appointed a Data Protection Officer (DPO) who is responsible for overseeing and ensuring that personal information is collected and processed in line with these principles. The contact details of the Data Protection Officer (DPO) can be found below:

Email address: dpo@nipd.com

Postal address: 31 Neas Engomis street, 2409 Engomi, Nicosia, Cyprus

Telephone number: + 357 22266888

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This Privacy Policy applies to NIPD Genetics facilities, its websites www.nipd.com, www.nipdlabs.com, www.nipdlabs.com.cy and their subdomains, that link to this privacy pol icy.

PERSONAL INFORMATION COLLECTION AND PROCESSING

We collect and process several types of personal information from and about users of our websites and of our products and services, including:

Information about children

If you are under 18 years of age, do not register on our website or provide any information about yourself to us. We do not provide our products or services directly to children or proactively collect their personal information. Despite this prohibition, it is possible that we may sometimes be given information about children while handling samples from our customers in our clinical labs, or through use of our products and services by our customers and partners. If we become aware that we have inadvertently collected personal information from children under the age of 18, without parental consent, we will take the necessary steps to delete it as soon as possible in compliance with applicable laws.

LEGAL BASIS FOR PROCESSING OF YOUR PERSONAL INFORMATION

Your personal information is collected by NIPD Genetics for the following purposes:

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  3. To process and respond to complaints. The legal basis for processing is to meet a legal obligation.
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To provide our products and services, NIPD Genetics may collect, receive and process biological samples to isolate and sequence DNA. NIPD Genetics may then store resulting genetic information and use genetic information to provide our products and services. In some cases, NIPD Genetics may provide interpretations of genetic information on behalf of its customers, including healthcare providers. This is only done pursuant to a written contract or a Sample Information Form with a patient’s informed consent and is subject to applicable legal and ethical safeguards.

This sensitive information described above is collected by NIPD Genetics for the following purposes:

  1. To provide support and maintenance services to customers who use our products and services – The legal basis for processing is to meet the requirements of a contract.
  2. To provide genotyping and sequencing services and analysis for our customers, including healthcare providers. The legal basis of this processing is to meet the requirements of a contract or as allowed in the Sample Information Form with a patient’s informed consent.
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Transfer of Data

Your information, including personal data, may be transferred to - and maintained on - computers located outside your province, country or other governmental jurisdiction where the data protection laws may differ than those from your jurisdiction.

If you are located outside Cyprus and choose to provide information to us, please note that we transfer the data, including personal data, to Cyprus and process it there.

Your consent to this Privacy Policy followed by your submission of such information represents your agreement to that transfer.

NIPD Genetics will take all reasonable steps necessary to ensure that your data is treated securely and in accordance with this Privacy Policy and no transfer of your personal information will take place to an organization or a country unless there are adequate controls in place including the security of your data and other personal information.

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NIPD Genetics complies with the General Data Protection Regulation and will not sell or trade your personal information.

NIPD Genetics may disclose your personal information in the good faith that such action is necessary:

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We use cookies and similar tracking technologies to track the activity on our websites and collect certain information. This includes information about the computer or device you are using, such as Internet protocol (IP) address, information about the browser type or version, the pages of our website that you visit, the time and date of your visit, the time spent on those pages, unique device identifiers and other diagnostic data.

You can instruct your browser to refuse all cookies or to indicate when a cookie is being sent. However, if you do not accept cookies, you may not be able to use some portions of our websites.

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Google Analytics is a web analytics service offered by Google that tracks and reports website traffic. Google uses the data collected to track and monitor the use of our service. This data is shared with other Google services. Google may use the collected data to contextualize and personalize the ads of its own advertising network.

You can opt-out of having made your activity on the Service available to Google Analytics by installing the Google Analytics opt-out browser add-on. The add-on prevents the Google Analytics JavaScript (ga.js, analytics.js, and dc.js) from sharing information with Google Analytics about visits activity.

For more information on the privacy practices of Google, please visit the Google Privacy & Terms web page

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We are committed to protecting the security of the information we collect, and we take reasonable physical, technical, and administrative safeguards such as data anonymization and encryption to help protect personal information from unauthorized or inappropriate access or use. It is your responsibility to protect the confidentiality of your passwords, and any other access features associated with your access or use of the website or our products and services, as well as to adhere to any applicable Terms of Use or other contract between us and you or your organization.

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We may employ third party companies and individuals to facilitate, maintain or operate our websites (“Service Providers”), to provide the websites on our behalf, to perform service-related services or to assist us in analyzing how our websites are used.

These third parties have access to your Personal Data only to perform these tasks on our behalf and are obligated not to disclose or use it for any other purpose.

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Our websites may contain links to other sites that are not operated by us. If you click on a third-party link, you will be directed to that third party's site. We strongly advise you to review the Privacy Policy of every site you visit.

We have no control over and assume no responsibility for the content, privacy policies or practices of any third-party sites or services.

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This Privacy Policy may be updated from time to time. We will notify you of any changes by posting the new Privacy Policy on this page.

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You are advised to review this Privacy Policy periodically for any changes. Changes to this Privacy Policy are effective when they are posted on this page.

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NIPD Genetics ensures that it can respond immediately to requests that you make for the exercise of your legal rights in accordance with data protection laws. These rights are as follows:

You also have the right to lodge a complaint at any time to the Office of the Commissioner for Personal Data Protection.

We encourage you to contact us, should you wish to practice any of your legal rights or you have any questions about this Privacy Policy, by sending an email to NIPD Genetics’ Data Protection Officer at dpo@nipd.com.

Effective date: 18/06/2021

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