Trisomy 18 is characterized by the presence of an extra 18 chromosome, within certain cells of the body or in each of these cells. Two forms of the disease are known and the severity of Down’s syndrome depends on it.

Trisomy 18, also called “Edwards Syndrome” is a disease caused by chromosomal abnormalities. It is defined by abnormalities in different parts of the body.

Patients with Trisomy 18 usually have growth disturbances before birth (intrauterine growth retardation). as well as an abnormally low weight. Other signs can also be related to the disease: heart attacks, deficiencies of other organs, etc.

Trisomy 18 also includes other characteristics: abnormal shape of the child’s skull, small jaw and narrow mouth, or even tucked-in wrists and overlapping fingers.

These different attacks can be vital for the child. In the majority of cases, a child with trisomy 18 dies before birth or before his first month.

Individuals who survive after the first month usually have significant intellectual disabilities.

The risk of Down’s syndrome is associated with pregnancy in a woman of any age. In addition, this risk is increased in the context of late pregnancy.

Two specific forms of the disease have been described:

• la full form : which concerns nearly 94% of babies with Down’s syndrome. This form is characterized by the presence of a triple copy (instead of two) of chromosome 18, in each of the cells of the body. Most babies with this form die before the pregnancy ends.
• la mosaic shape, which affects nearly 5% of babies with trisomy 18. In this context, the triple copy of chromosome 18 is only partially visible within the body (in certain cells only). This form is less severe than the full form.

The severity of the disease therefore depends on the type of trisomy 18 as well as the number of cells containing a copy of chromosome 18, in its.

The majority of cases of Trisomy 18 result from the presence of a triple copy of chromosome 18, within each cell of the body (instead of two copies).

Only 5% of individuals with Trisomy 18 have one too many, in certain cells only. This minority of patients are notably less prone to the risk of death before birth, or before the child’s first month.

More rarely, the long arm of chromosome 18 can attach (translocate) to another chromosome during cell reproduction or during embryonic development. This leads to the presence of the double copy of chromosome 18, coupled with the presence of an additional chromosome 18, and therefore to 3 chromosomes 18. Patients with this particular form of trisomy 18 exhibit partial symptoms.

The risk of Trisomy 18 concerns every pregnancy. Moreover, this risk is increased as the age of the pregnant woman increases.

In the majority of cases of Trisomy 18, the death of the child before birth, or during the first month, is associated with it. If the child survives, sequelae may be visible: developmental delay in certain limbs and / or organs, intellectual disabilities, etc.

Clinical signs and general symptoms may resemble Trisomy 18:

• a head smaller than average
• hollow cheeks and a narrow mouth
• long fingers that overlap
• large ears set very low
• deformities in the cleft lip

Other features of the disease may be visible:

• kidney and heart damage
• refusal to feed, leading to deficiencies in the development of the child
• breathing difficulties
• the presence of hernias in the stomach
• abnormalities in the skeletal system and in particular in the spine
• significant learning difficulties.

The risk factor for the development of Trisomy 18 is genetics.

Indeed, the presence of a triple copy of chromosome 18, within certain cells only or even in each cell of the organism, can lead to the development of such a pathology.

No treatment for Trisomy 18 is currently known. The management of this disease is effective by a multidisciplinary health team.

Treatments can nevertheless be prescribed, and this in the context of heart attacks, infections, or eating difficulties.

La physiotherapy can also be treated for Trisomy 18, particularly if the muscle and bone systems are impacted.