Today, lets look at a syndrome that affect about 1 in every 5,000 births. Also, 9 out 10 babies with the syndrome dies during their first year and about 1 in 10 babies with less severe form of the syndrome, for example partial or mosaic trisomy 13, live for more than a year. This syndrome is called ‘Patau’s syndrome’ and the risk of having a baby with it increases with the mothers age. So, let’s try and understand it and the factors that lead to it.
Patau’s syndrome is a severe rare genetic disorder caused by having an additional copy of chromosome 13 in some or all the body’s cell. Its also know as trisomy 13. Normally, each cell contains 23 pairs of chromosomes, which carry genes you inherit from you parents. However, a baby with Patau’s syndrome has 3 copies of chromosome 13, instead of 2.
As a result, this severely disrupts normal development and, in many cases, results in stillbirth, miscarriage or the baby dying shortly after birth. Babies with this syndrome grow slowly in the womb and have low birth weight, along with other number of medical problems.
Symptoms and features
Babies with this syndrome can have a verity of health issues. The growth in the womb is often slow and restricted, resulting in a low birth weight. Also, 8 out 10 will be born with severe heart condition or defects. The baby’s brain does not divide into two halves ordinarily. This is known as holoprosencephaly. When this happens, it affects the facial features and causes defects for instance:
- An abnormally small eye or eyes (microphthalmia)
- Reduced distance between the eyes (hypotelorism)
- Cleft lips and palate
- Issues with the development of nasal passages#
Other abnormalities of the face and head include:
- Skin missing from scalp (cutis aplasia)
- Smaller than usual head size (microcephaly)
- Ear malformation and deafness
- Raised, red birthmarks (capillary haemangiomas)
Patau’s syndrome can also cause other health problems like:
- Abnormal small penis in boys
- An enlarged clitoris in girls
- Abnormal cysts in kidneys
- An abnormal wall defect where the abdomen does not develop fully in the womb, resulting in the intestines being outside the body, covered only by the membrane – also know as Omphalocele or Exomphalos.
Other abnormalities are:
- Extra fingers or toes
- Rounded bottom to the feet (Rocker-bottom feet)
Causes of Patau’s syndrome
This syndrome is cause by chance and is not as a result of something the parents have done. Most cases of the syndrome do not run in the families (not inherited). The occur randomly during conception, when the sperm and the egg combine, and the foetus start to develop.
The extra chromosome is added as a result of an error during the copying or part of the copying of chromosome 13, which severely affects the baby’s development in the womb. In many cases, the baby dies before reaching full term (miscarriage) or dead at birth (stillbirth).
In most cases of Patau’s syndrome, a baby has a whole extra copy of chromosome number 13 in their body’s cells. This is sometimes known as trisomy 13 or simple trisomy 13. Furthermore, up to 1 in 10 cases of Patau’s syndrome, genetic material is rearranged between chromosome 13 and another chromosome. This is called a chromosomal translocation.
Patau’s syndrome that arises because of this can be inherited. Genetic Alliance UK has more information about chromosome disorders. However, in a further 1 in 20 cases, only some cells have the extra copy of chromosome 13. This is known as trisomy 13 mosaicism. Occasionally, only part of 1 chromosome 13 is extra (partial trisomy 13).
The symptoms and features of both mosaicism and partial trisomy tend to be less severe than in simple trisomy 13, resulting in more babies living longer.
Screening of Patau’s syndrome
You’ll be offered a screening test for Patau’s syndrome, as well as Down’s syndrome (trisomy 21) and Edwards’ syndrome (trisomy 18), from 10 to 14 weeks of pregnancy. The test assesses your chances of having a baby with these syndromes.
The screening test offered at 10 to 14 weeks of pregnancy is called the combined test because it involves a blood test and an ultrasound scan. If the screening tests show that you have a higher risk of having a baby with Patau’s syndrome, you’ll be offered a diagnostic test to find out for certain whether your baby has the syndrome. This test will check your baby’s chromosomes in a sample of cells taken from him or her
Treating and managing the syndrome
There’s no specific treatment for Patau’s syndrome. As a result of the severe health problems a newborn baby with the syndrome will have, doctors usually focus on minimising discomfort and ensuring the baby is able to feed.
For the small number of babies with Patau’s syndrome who survive beyond the first few days of life, their care will depend on their specific symptoms and needs. If your baby is diagnosed with Patau’s syndrome, either before birth or shortly afterwards, you’ll be offered counselling and support.