What Causes Patau Syndrome & is it Treatable?

Patau Syndrome is a genetic condition, which is generally fatal as it gives rise to complicated heart diseases and serves as host for various other diseases. This syndrome is characterized by the presence of an additional genetic material, which comes from the chromosome 13. This additional genetic material may be present in certain cells or all the cells of the human body. In a general human body, the chromosome number 13 is present twice whereas, in people who are suffering from Patau Syndrome, the chromosome 13 is present thrice, thereby leading to the rise of abnormalities.

It is a rare condition and occurs in one child out of eight thousand to twelve thousand live births. The babies born with this syndrome have abnormalities in almost every organ present in the body, thus they can easily die due to multiple organ failures. They also suffer from developmental delays and are quite small in size as compared to the other children of their age. The family history of the disease or having a close relative suffering from the same condition increases the risk of a pregnancy with Patau Syndrome.

Patau Syndrome is also referred as Trisomy 13; however this is actually a type of the syndrome. The children born with this condition normally die within ten to fifteen days of their birth. A small fraction of the children born with Patau Syndrome manage to survive for up to one year. It is quite difficult to predict the life expectancy of the children born with this syndrome as the extent of the abnormalities present in their organs cannot be tracked right upon their birth. At most, the children born with this syndrome live for as long as ten years.

As told earlier, Patau syndrome is a congenital condition which is caused due to the trisomy of the chromosome 13. Apart from this, the presence of the extra genetic material attached to the chromosome leads to the certain mutation which causes this syndrome. In a majority of the cases, it is not inherited from the parents’ cells. It occurs due to some random mutations occurring during the production of the egg cells or sperm cells.

In some rare cases, the additional genetic material is found to be shared between chromosome 13 and another chromosome. This condition is known as chromosomal translocation. Patau syndrome caused due to translocation is hereditary.

At times, just a portion of chromosome 13 is found in all the three copies of the chromosomes present in all the cells of the human body. This syndrome is called partial trisomy 13.

The embryos which are conceived as a result of sexual intercourse between relatives (blood-related individuals) are believed to carry genetically mutated cells, which later transform into Patau syndrome. Such couples are advised to consult a genetic counselor before planning a pregnancy as the counselor can easily point out the genetic disorders that the child is likely to face and will draw attention to the ways by which this condition can be avoided.

In some people suffering from Patau syndrome, they have an additional copy of chromosome 13 in only certain cells of the body. This is called mosaic trisomy 13. The seriousness of mosaic trisomy 13 syndrome is dependent on the nature and the proportion of cells which possess the extra chromosome. .

The children suffering from Patau syndrome can have some of these deformities.

• In the ultrasounds taken in the fifth and sixth month, doctors can easily locate abnormalities in the internal organs of the still-developing embryo.
• The embryos of the children suffering from Patau Syndrome have fused cerebral hemisphere which can be easily seen on MRI or CT scan.
• They often face episodes of temporary cessation of spontaneous breathing.
• In most of the children suffering from this syndrome, a cleft lip is visible which helps to easily diagnose this syndrome.
• They suffer from an intellectual disability and other physical deformities.
• The children suffering from Patau Syndrome possess an extra pair of toes and fingers.
• They do not grow eyebrows.
• The children have no eyes or even if the eyes are present, they are quite small comparatively.
• The children have malformed ears which are dysplastic in appearance.
• In the male child, the testes are either abnormally formed or it does not descend from the scrotal region as the child grows up.

Patau syndrome can be diagnosed during the early stages of pregnancy. In the ultrasounds conducted during the first trimester of the pregnancy period, the abnormalities are quite visible. The internal organs of the embryo either have delayed development or they are abnormally developed. Once the ultrasounds obtained convince the doctor that something is wrong with the embryo, physician may conduct an MRI or CT scan as the deformities are prominently seen in an MRI or CT scan. To confirm the syndrome further, the doctor may study the character of the chromosomes. If the syndrome is present, then trisomy of chromosomes can be observed. Apart from that, the doctors also conduct teats like cell-free DNA screening test, Non-invasive prenatal testing (NIPT) or Pregnancy-Associated Plasma Protein- A (PAPP-A) test to confirm the syndrome.

However, unlike the other congenital conditions, the screening of the mother’s serum does not provide any useful results. A special type of sonography called ultrasonography- holoprosencephaly is preferred which in case shows the presence of pathognomonic features, the existence of the syndrome in the embryo is confirmed. Moreover, tests like Chorionic Villus Sampling (CVS) and Amniocentesis are used to completely confirm the presence of the syndrome.

There isn’t any specific treatment for this syndrome. Some children who are diagnosed with Patau Syndrome have incurable severe defects from birth. However, certain measures can be taken to extend their lifetime. It is difficult to survive for them even for a few months. Surgery is definitely required to fix certain defects in order to expand their years of survival. Critical defects like holes in the heart and cleft defects need to be mended immediately. As they suffer from developmental delay, giving them regular speech training and physical therapies has proven to be quite effective. If the syndrome has been prenatally diagnosed, the parents can opt to end the pregnancy as the chances of survival of the child is quite low.

Once the first child has been diagnosed with Patau Syndrome, the parents are advised to take genetic counseling to discuss the further chances of their second child to be affected by the same condition and the ways by which they can avoid this situation and can conceive a normal child.

This genetic anomaly is not gender oriented and the chance of being affected by this syndrome is same in both the genders.