Trisomy Disorders

Trisomies generally happen at random, but are nevertheless associated with older maternal age. The later the pregnancy, the greater the chance the fetus will be affected by trisomy (CUCKLE, H.S., et al., 1987).

If the chosen screening test shows a high probability of trisomy 21, 18 or 13 (if NIPT was used), the healthcare professional will recommend a diagnostic test. This test helps confirm whether or not the baby is affected by trisomy or a sex chromosome anomaly. However, diagnostic testing is invasive, involving certain risks of complications that can sometimes lead to miscarriage. For this reason, the test is not offered from the beginning.

Two methods are available for obtaining the sample required for the diagnostic test: chorionic biopsy and amniocentesis. The healthcare professional will guide the pregnant woman based on her personal situation.

Amniocentesis

Amniocentesis consists of inserting a fine needle into the abdomen to collect a small amount of the amniotic fluid surrounding the baby in the uterus. This fluid contains fetal cells that can be analyzed for chromosomes. This test can be performed as early as the 15th week of pregnancy.

Chorionic villus biopsy

Chorionic villus biopsy consists of collecting a small sample of placenta, known as the chorionic villi. This ultrasound-guided procedure can be performed via the abdomen or the vagina. It is generally done between the 11th and 14th weeks of pregnancy. In a minority of cases, an amniocentesis may still be necessary following a chorionic biopsy.

Once the tests are completed, you may be faced with the difficult choice of continuing or terminating the pregnancy. In these circumstances, do not hesitate to discuss the matter with your healthcare professional or the people around you. Support groups are also available in various regions of Quebec. You can contact your local CLSC for more information.

Keep in mind that this is not a routine examination. The decision whether or not to undergo these tests is entirely up to you. If you have any questions, feel free to discuss them with your healthcare professional.

Yes, tests can be done following childbirth to screen the baby for trisomy.

The pediatrician can detect typical physical signs of trisomy during a clinical examination. For trisomy 21, for example, these signs may include specific facial features, hypotonia (low muscle tone) and abnormalities in the hands and feet.

However, while clinical examination may suggest trisomy, it is not sufficient for a definitive diagnosis.

A karyotype is a test to analyze the baby’s chromosomes. It is performed on a blood sample. A karyotype can accurately confirm the presence of trisomy 21, 18 or 13 by revealing the extra copy of the chromosome.

This test, also known as “FISH,” offers a number of several additional advantages compared to karyotyping, such as identifying duplications or deletions of small portions of chromosomes. It is also done on a blood sample. This means that CMA can detect subtle chromosomal abnormalities that may not be visible on a standard karyotype.

To sum it up, a clinical examination after birth may initially suggest the presence of trisomy, but genetic tests such as a karyotype or chromosomal microarray analysis are needed to confirm the diagnosis. These tests do not present any significant risk for the baby and can accurately determine the presence and type of trisomy, thereby ensuring appropriate care for the baby and proper support for the family.

The arrival of a child with trisomy can lead to a period of questioning and require adjustments. The Canadian Down Syndrome Society offers a wealth of resources for new parents who are expecting or have recently had a child with Down syndrome (trisomy 21).

Here are a few ways to address the needs of a child with Down syndrome:

1. Find out more about your child’s situation, so that you can identify their needs. You can visit Facebook groups for parents of children with trisomy. A number of support associations also exist in the province, such as, the Quebec Intellectual Disability Society [AISQ] and the Regroupement pour la Trisomie 21 [RT21]. Your healthcare professional can direct you to various resources.
2. Share what you learn with family and friends, so that they can,too, better understand your child and offer the right support.
3. Plan regular medical follow-ups to monitor and treat any health complications.
4. Maintain a stable routine, so that the child feels safe and secure, and make sure your home is adapted to the child’s needs, for example in terms of mobility assistance.
5. Foster the child’s social and emotional development through group activities and adapted play activities that stimulate sensory and motor development.
6. Include the child in the various spheres of social life, to help them develop emotional relationships, fulfill their potential and live as independently as possible.

Above all, it is important to be there for the child, show patience so that they can develop at their own pace, and do not hesitate to ask for additional help and support.