It is only natural for parents to feel anxious about the future of a child with an intellectual disability.
How common are these intellectual disabilities?
Detailed information on intellectual disabilities can be found on other pages of this site, but the conclusion is that not all intellectual disabilities can be detected by NIPT.
This is because intellectual disabilities often occur independently of genetics. However, it is a natural parental instinct to want to exclude that possibility as much as possible before birth.
Is it possible to detect intellectual disabilities with the three types of NIPT tests (Chromosomes 13, 18, and 21) performed at most facilities?
Only the test for Chromosome 21 (Down syndrome) targets intellectual disability. For Trisomy 13 and 18, the physical disabilities are so severe that it is difficult to even recognize the intellectual disability. In other words, the condition is so severe that the child often passes away too early to determine if an intellectual disability exists.
However, isn’t what parents worry about most the scenario where the child grows physically but remains intellectually disabled?
If this can be known prenatally, it is parental love to want to detect as many conditions as possible. Let us consider in what cases intellectual disabilities occur.
In the case of Trisomy 13 and 18 mentioned earlier, the reason intellectual disability is not the sole focus is that these chromosomes carry so many vital genes that cases presenting only intellectual disability are rare. Since many genes related to life support are also present, sustaining life becomes difficult before intellectual disability even becomes an issue. So, what happens if there is an abnormality in the number or sequence of some genes? While life can be sustained, it often involves impairment of the brain, a highly advanced function, resulting in intellectual disability.
NIPT is basically a test to check the “quantity” of chromosomes. Since it cannot check for sequence abnormalities, NIPT can only detect partial changes in chromosomal quantity. However, among genetic abnormalities, quantity abnormalities are more common than sequence abnormalities. Therefore, NIPT is very useful because it can check for these quantity abnormalities.
So, how can we test for such intellectual disabilities?
First, those who have seen this website may have realized that there are multiple options for NIPT. That means there are tests other than the 13, 18, and 21 chromosome tests recommended by obstetricians. These “other tests” are widely performed around the world. Particularly famous are sex chromosome abnormalities. Microdeletion syndromes, involving the loss of a small part of a chromosome, are also well-known conditions. This is because DiGeorge syndrome, which is included in this category, is said to be the second most common cause of intellectual disability. It follows Down syndrome in frequency. The average life expectancy is said to be around 50 years. As mentioned earlier, since only a part of the chromosome is missing, life can be sustained, and with current medical care, patients can live into their 50s or 60s. However, their intelligence is around IQ 50, which makes it difficult to live independently. Also, sex chromosome abnormalities are associated with infertility and growth disorders. Knowing this early allows for the prevention of growth disorders, and if the individual knows they have a high probability of infertility, they can access advanced medical procedures such as TESE. Regarding sex chromosome abnormalities, even if they do not reach the level of intellectual disability, they are commonly accompanied by learning disabilities. Detailed information on these topics is written on each page, so please take a look.
What I want to say here is that NIPT is not limited to just three types. Nowadays, various tests are available, making it possible to detect conditions involving intellectual and developmental disabilities early on, many of which are completely untreatable. I harbor a certain anxiety about the fact that NIPT is gradually spreading without these facts being fully conveyed to pregnant women.
More details are written on this website, so please read through it. If the text alone is difficult to understand, we provide YouTube videos every day. Please refer to those as well.