What are chromosome abnormalities?

What is a chromosomal abnormality?

A chromosomal abnormality is any alteration from the normal distribution in humans. Let's keep in mind, first of all, that the normal chromosomes are 23 pairs , with the 23rd pair containing the sex chromosomes (XX in women, XY in men).

Chromosome abnormalities can be of two types: numerical or structural. First, there may be a different or fewer chromosomes than usual. The second is that one of the chromosomes may be damaged, mislocated, or mutated .

It should be noted that genetic disorders can sometimes be detected early, during pregnancy. What's more, it's also possible to perform genetic comparisons between people who are planning to conceive a child.

The truth is that anomalies give rise to various problems that need to be addressed as soon as possible. Take note...

What are the consequences of a chromosome abnormality?

Chromosome abnormalities often lead to various conditions and diseases . The most common are:

1. Down syndrome

Down syndrome , or trisomy 21 , is one of the most common abnormalities. Most often, it involves a person having an extra copy of chromosome 21 ; therefore, instead of 46 chromosomes, they have 47. However, it is also possible to have Down syndrome due to chromosome translocation , or mosaicism .

The consequences of this abnormality can be related to cognitive problems (intellectual disability) or various physical problems . However, today, the quality of life expectations for a person with Down syndrome are much higher.

2. Klinefelter syndrome

Klinefelter syndrome is specific to males and, due to its characteristics, is usually not identified until adulthood. It consists of having an extra copy of the X chromosome , on the 23rd pair. What are the consequences? Lower testosterone production and, tangentially, smaller testicles, less hair, less muscle, and more breast tissue. Unlike other genetic disorders, life expectancy is usually higher.

3. Turing Syndrome

Turing syndrome is another common chromosomal abnormality , occurring exclusively in girls . It involves the complete or partial absence of the X chromosome , which is known as monosomy . The consequences are varied, including decreased physical development and infertility when they reach adolescence. Life expectancy is usually short, although it has recently increased.

4. Trisomy 13

Trisomy 13 , which involves an extra copy of chromosome 13 or genetic material from this chromosome in other cells, causes various physical and cognitive developmental problems. However, we must note that the severity of Patau Syndrome varies depending on the case, although only 13% of babies reach the age of 10. This is, therefore, one of the most serious genetic diseases in existence.

5. Trisomy 18

Finally, we must mention trisomy 18 , also known as Edwards syndrome, which involves an extra copy of chromosome 18 , although it can also occur due to translocation. It manifests from birth, and babies generally have a very low life expectancy due to its physical and cognitive consequences.

How to detect a chromosomal abnormality?

The first thing to note is that it's possible to detect a chromosomal abnormality before conception and birth . What genetic testing methods are available? Here we'll tell you about them...

Genetic compatibility testing before pregnancy

The best way to check the chances of a healthy pregnancy is with a genetic compatibility test . In this case, a sample is taken from each partner to determine whether they are genetically compatible . This is always recommended, but it's especially important if there are family precedents or if you have a family relationship.

What this test does is let you know the likelihood of having some type of genetic malformation. And it's certainly worthwhile if you want to opt for natural conception or other methods of conception.

During pregnancy

There are numerous genetic tests during pregnancy that allow you to monitor your pregnancy's progress. We highlight the following:

Blood test

Blood tests during pregnancy are common . A blood test can predict, for example, Down syndrome with a very high probability, but also Patau syndrome or Edwards syndrome, among others. It can usually be done starting from the 10th week of pregnancy .

Amniocentesis

Amniocentesis , performed between weeks 10 and 15 of pregnancy , involves taking a sample of amniotic fluid to check for possible chromosomal abnormalities. It is a common test and can detect Down syndrome, among other genetic disorders.

Chorionic biopsy

A chorionic villus sampling (CVS) is a tissue sample taken from the placenta to detect possible diseases. It can be performed starting around week 11 of pregnancy . It's a well-established technique, recommended for people at risk, and can detect Down syndrome and Turner syndrome.

Triple Screening

The triple screening is a comprehensive test that can detect various problems. First, this triple screening for chromosomal abnormalities can identify potential risks for Down syndrome or Edwards syndrome. You must first have an ultrasound from week 12 of pregnancy, and remember that this is not a diagnostic test.

In summary…

Knowing about chromosomal abnormalities is essential to minimize risks, as is testing before and during pregnancy. At Genotica, we offer various genetic testing options in Spain at the best price. Contact us and compare to choose the best one for you!