Trisomy Awareness Month

Trisomy is a genetic condition where a chromosome has 3 copies instead of the normal two. March, the third month of the year, is Trisomy Awareness month. While some trisomy conditions, like Trisomy 21 (Down syndrome), Trisomy 18 (Edward’s syndrome) and Trisomy 13 (Patau syndrome) are well known, there are more trisomy syndromes that receive little recognition yet play a critical part in pregnancy, survival, and an individual’s health.

To understand the significance of trisomies, one must first acknowledge the role and mechanisms of chromosomes. Chromosomes carry ‘the recipe’ for characteristics that are passed from parents to their offspring, like eye and hair color, within genes. Genes make up all the genetic information of a person, and also control protein functions that are essential for our bodies to work properly. Accordingly, chromosomes define the features and the health of an individual.

Each species has a set number of chromosomes which carry a number of genes that code for certain characteristics and proteins. Ranging from 2 chromosomes in a species of roundworm to 1260 in a type of fern plant, potatoes have 48, horses have 64, and humans normally have 46 chromosomes arranged in 23 pairs. From these 23 pairs, 22 pairs are called ‘autosomal’. These are chromosomes 1 to 22 that control general genes and functions of our body. Chromosome pair 23 contains the sex chromosomes. These determine the gender of an individual, with females carrying two X chromosomes (XX), and males carrying an X and a Y (XY).  From an evolutionary standpoint, the chromosome number doesn’t matter – it’s the number of genes on the chromosomes that is significant. These can be spread out on the chromosomes or, as in humans, be closely packed together.

Half of each chromosome pair is inherited from the father, and the other half is inherited from the mother. During cell division, when chromosomes divide and make new ‘daughter’ cells that carry the same genetic information, chromosome numbers must divide equally.

Problems arise when there is an abnormal number of chromosomes, leading to an excess or a depletion of genes that disrupt the genetic balance. In most cases concerning the autosomal chromosomes, these errors occur due to increased maternal age. While sperm is continually produced in a male, with the average sperm production taking about 65 days, all the oocytes – that will mature into eggs – of a female are already produced since she was a fetus. Therefore, a female egg is chronologically the same age as the woman. The older the eggs are, the more likely the repair mechanisms that are in place to prevent mistakes in cell division will fail.

Trisomies occur during errors in cell division. During reproduction, the egg and the sperm, carrying 23 chromosomes each, fuse together and create a zygote of 46 chromosomes. This single cell will repeatedly multiply and divide its genetic material, cell by cell, to form the fetus, the placenta and the umbilical cord. During fertilization and early development cell divisions, mistakes can occur and cells can end up with a higher or lower number of chromosomes. For example, a cell can end up with 3 copies of chromosome 18. If this copy is not corrected through the organism’s repair mechanisms, it can end up in the developing embryo. The error will be repeated in all subsequent daughter cells as the faulty cell continues to divide, and the baby will have a high risk of developing Trisomy 18. The severity of the condition depends on whether the trisomy affects the whole chromosome or is partial (duplication), how early in the development stage the error occurred – which determines the percentage of abnormal to normal cells (mosaicism) – and on the affected chromosome.

Sex chromosome trisomies, concerning the 23rd pair of chromosomes, are hypothesized to be due to paternal errors in failing to properly separate the X and Y chromosomes1. Such trisomies, like Triple X (XXX), or Klinefelter syndrome (XXY), can affect life quality, but not survival. Symptoms include delayed development, infertility and mild to moderate distinct appearance. Difficulty in postnatal diagnosis is common due to symptoms variability and usually happens after adulthood, so Non Invasive Prenatal Testing (NIPT) is useful for early clinical management. Generally, they are less severe than autosomal trisomies. This is due to the ‘X-inactivation’ mechanism, that always ‘shuts off’ one of the two X chromosomes so females don’t have twice the number of genes as males – which could be toxic. Interestingly, the same X doesn’t get silenced in all cells – the process is random – explaining the symptom variability in sex chromosomes disorders. This is why tricolor, calico and tortoiseshell cats are primarily females; their fur color gene that carries 2 color variations is X-linked.

Trisomies 21, 18 and 13 are the most well-known autosomal aneuploidies, as they are the only trisomies resulting in a liveborn infant. Children affected by these trisomies have a range of birth defects like heart abnormalities, delayed development and intellectual disabilities. Trisomy 21 has the milder clinical presentation of the three. A very high percentage of children with Down syndrome have serious heart defects; however, most individuals cope well when having a close support system. Fetal mortality is high in Trisomies 18 and 13, and less than 15% of babies survive past their first year of life2,3. These trisomies affect survival and quality of life, however there are other trisomies that also affect pregnancy viability.

50-70% of pregnancy losses are due to chromosomal abnormalities, with autosomal trisomies accounting for 60% of these losses4. Trisomies 16 and 22 are the commonest causes of spontaneous miscarriage during pregnancy, with most losses happening in the first trimester. Unfortunately, there is no prevention or treatment. In the exceptionally rare event that babies are carried to term, they are unable to survive for more than a few days due to the severity of birth defects that include heart and kidney abnormalities, and muscle weakness. Trisomies 8 and 9 are also severe, resulting in newborn death within the first months or days of life. These conditions are extremely rare, and are characterized by heart defects, cleft palates, joint malformation and kidney problems.

Trisomy Awareness Month is celebrated to spread knowledge, support and understanding about children affected with trisomies and their families. It’s a time to raise awareness on the challenges faced, remember all the lost pregnancies and the babies that have been sadly gone. Unfortunately, the exact mechanisms leading to trisomies are unknown and their prevention is impossible. NIPT for the detection of trisomies 21, 18, 13, X and Y early in the pregnancy are available, which make it possible for prospective parents to receive all the necessary information about the health of their baby as soon as possible. This enables them to take informed decisions about crucial medical management, their pregnancy and the future of their family.

VERACITY and VERAgene both test for autosomal and sex chromosome trisomies from the 10th week of pregnancy. For more information, please visit www.nipd.com

References:

  • Bacino et al. (2011). ‘Chapter 76: Cytogenetics’. In Kliegman RM et al. Nelson Textbook of Pediatrics, 19th Edition, Philadelphia: Saunders. Pp 394-413.
  • Cereda A. and Carey J.C. (2012). ‘The trisomy 18 syndrome’. Orphanet Journal of Rare Diseases, 7:81.
  • Peroos S. et al. (2012). ‘Longevity and Patau syndrome: what determines survival?’ Case Reports, 2012:bcr0620114381
  • Silver R.M. and Branch D. (2007) ‘Sporadic and Recurrent Pregnancy Loss’. Clinical Obstetrics: The fetus & mother, 3rd edition, Blackwell Publishing, Boston, pp 143-160.


Share
View All Posts

NIPD Genetics - Privacy Policy

General Statement

This Privacy Policy applies only to www.nipd.com and its subdomains (hereafter collectively referred to as “Sites") that link to this policy. NIPD Genetics Sites are owned by NIPD Genetics Public Company Ltd and are operated by NIPD Genetics Public Company Ltd and on occasion by a third-party that is responsible for the technical maintenance of the Sites.

If, you do not agree with this Privacy Policy, please do not access or use any of NIPD Genetics Sites.

NIPD Genetics values your interest in NIPD Genetics, its products and its services. NIPD Genetics takes the protection of your data seriously.

Personal data for purposes of this Privacy Policy, is any information by which you can be individually identified, including, but not limited to, your name, profession, address, e-mail address, and telephone number.

You may contact NIPD Genetics Public Company Ltd at
NIPD Genetics Public Company Ltd
Neas Engomis 31
Engomi, Nicosia
2409, Cyprus

NIPD Genetics Data Protection Officer can be reached at dpo@nipd.com

This Privacy Policy applies only to the Sites as defined above and which are operated by NIPD Genetics. The NIPD Genetics Privacy Policy seeks to inform the users of its Sites of the following:

NIPD Genetics will not use or share your information with anyone, except as described in this Privacy Policy. This Privacy Policy does not apply to any information we might collect by other digital and offline means and or from other digital and offline sources. The use of information collected through our Sites shall be limited to the purposes under this Privacy Policy and our Terms of Use to customers.

This page informs you of our policies regarding the collection, use, and disclosure of personal data when you use our Sites and the choices you have associated with that data.

We use your data to provide and improve the Sites. By using the Sites, you agree to the collection and use of information in accordance with this policy. Unless otherwise defined in this Privacy Policy, terms used in this Privacy Policy have the same meanings as in our Terms and Conditions, accessible from www.nipd.com

Type of personal information NIPD Genetics may collect through its Sites

Information Collection And Use

We collect several different types of information for various purposes to provide and improve our Sites and services to you.

Personal Data

While using NIPD Genetics Sites, you may be asked to provide NIPD Genetics certain personally identifiable information that can be used to contact or identify you ("Personal Information"). Personal Information that might be used to identify you includes, but is not limited to:

If you send us a query via our Contact us form, your email address, the content and any follow up emails are retained indefinitely.

Cookies and Usage Data

Usage Data

We may also collect information how the Sites are accessed and used ("Usage Data"). This Usage Data may include information such as your computer's Internet Protocol address (e.g. IP address), browser type, browser version, the pages of our Sites that you visit, the time and date of your visit, the time spent on those pages, unique device identifiers and other diagnostic data.

Tracking & Cookies Data

We use cookies and similar tracking technologies to track the activity on our Sites and hold certain information.

Cookies are files with small amount of data which may include an anonymous unique identifier. Cookies are sent to your browser from a website and stored on your device. Tracking technologies also used are beacons, tags, and scripts to collect and track information and to improve and analyze our Sites.

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 Sites.

Examples of Cookies we use:

Session Cookies. We use Session Cookies to operate our Sites.

Preference Cookies. We use Preference Cookies to remember your preferences and various settings.

Security Cookies. We use Security Cookies for security purposes.

Visitor behavior cookies. To understand how visitors use and navigate the Sites

Keyword cookies. To understand how visitors discover the Sites.

Use of Data

www.nipd.com uses the collected data for various purposes:

Transfer of Data

Your information, including personal data, may be transferred to — and maintained on — computers located outside of 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.

www.nipd.com 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 data 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.

Disclosure of Data

NIPD Genetics complies with the protection of personal data regulation and will not sale or trade your personal data.

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

Security of Data

The security of your data is important to us, but remember that no method of transmission over the Internet, or method of electronic storage is 100% secure. While we strive to use commercially acceptable means to protect your Personal Data, we cannot guarantee its absolute security.

Service Providers

We may employ third party companies and individuals to facilitate, maintain or operate our Sites ("Service Providers"), to provide the SItes on our behalf, to perform service-related services or to assist us in analyzing how our Sites is 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.

Analytics

We may use third-party Service Providers to monitor and analyze the use of our Sites.

Google Analytics

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

Access to your personal data, correction, deletion, and Opting Out

You have the right to review, update or delete any of your personal data by sending a request at NIPD Genetics Personal Data Officer pdo@nipd.com

Links to Other Sites

Our Sites 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.

Children's Privacy

Our Service does not address anyone under the age of 18 ("Children").

We do not knowingly collect personally identifiable information from anyone under the age of 18. If you are a parent or guardian and you are aware that your Children has provided us with Personal Data, please contact us. If we become aware that we have collected Personal Data from children without verification of parental consent, we take steps to remove that information from our servers.

Changes to This Privacy Policy

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

We will let you know via email and/or a prominent notice on our Service, prior to the change becoming effective and update the "effective date" at the top of this Privacy Policy.

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.

Contact Us

If you have any questions about this Privacy Policy, please contact pdo@nipd.com

Ok got it!