The number of chromosomal diseases is huge and one of them is Patau syndrome. The karyotype of a patient with a similar diagnosis is changed, which is displayed on the work of the whole organism. Pathology affects the structure of the skeleton, the work of the nervous, excretory, reproductive and cardiovascular systems.
Many parents today are interested in any additional information about this pathology. What is Patau syndrome? The karyotype and phenotypic characteristic, diagnostic and treatment methods, symptoms and causes are all interesting points. Such issues are worth exploring in more detail.
Patau Syndrome: Karyotype and General Information
To begin with, it’s worthwhile to deal with general data. What is Patau syndrome and how does it develop? Chromosomes with such a pathology do not diverge in the process of formation of gametes or zygotes, which leads to a lot of disorders in the process of embryonic development.
Patau syndrome is called a congenital disease that is associated with trisomy of the 13th pair of chromosomes - the child receives an extra chromosome. The karyotype formula in this case may look as follows: 47, XX, 13 + (for girls), 47, XY, 13 + (for boys). This is an extremely dangerous and serious disease, which is accompanied by the formation of multiple malformations - they are often incompatible with life, so the child dies in the womb.
Brief historical background
The first symptoms of this pathology were described in 1657 in the works of the Danish scientist Erasmus Bartolin. Nevertheless, the chromosomal nature of the disease was proved by Dr. Klaus Patau in 1960 (the syndrome was named in his honor).
Cases of such congenital abnormalities have been described by scientists who have studied the tribes of the Pacific Islands. It is believed that the frequent chromosomal mutations in this geographical area were caused by radiation damage that appeared after testing nuclear weapons.
Causes of the disease
As already mentioned, Patau syndrome is characterized by trisomy of the thirteenth pair of chromosomes. Moreover, in most cases (according to statistics, in 80%) there is a nondisjunction of the thirteenth chromosome precisely during meiosis. Most often, the child receives a full pair of chromosomes from the mother. Sometimes there is Robertson translocation, in which the embryo already receives an additional copy of the genes.
It is proved that genetic failure can occur during the formation of the gamete or later - with the formation of the zygote.
To date, the causes of the mutation have not been established - it is believed that it occurs completely by accident. The role of infections, bad habits, and somatic diseases of the mother in the development of this pathology in the fetus is also unknown.
Types of pathology
To date, several forms of this disease are distinguished.
- Simple form. In this case, disorders occur in the early stages of embryo development. Moreover, each cell of the body contains an extra chromosome in the thirteenth pair.
- Mosaic form. Similar changes occur already at later stages of fetal development. However, some organs consist only of healthy cells, while pathologically altered cells are contained in other tissues and organs. With this form of the disease, symptoms may be less pronounced.
Are there any risk factors? What can trigger a mutation?
Patau syndrome develops spontaneously and, alas, impossible to prevent it. Nevertheless, scientists identified several unfavorable factors.
- It is believed that the risk of such a pathology increases if the mother lives in an area with a poor environmental situation.
- As already mentioned, radiation exposure plays a role in the appearance of spontaneous chromosomal mutations.
- It is also noted that the likelihood of various chromosomal and genetic mutations increases in the case of late pregnancy (mother over 45 years old).
- Risk factors include the presence of hereditary diseases in previous generations of parents.
- It has been proven that cases of genetic and chromosomal mutations are becoming more frequent when it comes to marriages between close relatives.
Symptoms of pathology during pregnancy
As already mentioned, the karyotype formula for Patau syndrome has been changed, but it is impossible to detect this without special tests. However, often such a pregnancy is accompanied by polyhydramnios. According to statistics, the time of gestation is also reduced - an average of about 38.5 weeks. It is worth noting that with such a pathology, pregnancy is often interrupted. There is a great risk of stillbirth.
Patau syndrome: photos and hallmarks
Children with a similar mutation have a number of special phenotypic characteristics. To begin with, it is worth saying that babies give birth on time, but with a small weight - prenatal hypotrophy takes place (the weight of a full-term baby with a similar diagnosis rarely exceeds 2500 g). The birth process itself is also often associated with complications, in particular asphyxia of the newborn.
A child with a chromosomal mutation has a number of congenital deformations of the brain and facial part of the skull. There is microcephaly - the circumference of the baby's head is much less than the norm. In children with Patau's syndrome, the forehead is often low and sloping, the nose is flat and sunken, and the eye slits are narrow. Auricles, as a rule, are deformed and are located low.
A typical symptom is the presence of bilateral clefts of the face, in particular, the so-called cleft palate (pathology is accompanied by splitting of the tissues of the soft and hard palate, with the nasal and oral cavities communicating with each other), as well as the cleft lip (cleft lip). The doctor may suspect the presence of this chromosomal mutation already in the first parts after the birth of the baby.
Pathology from other organ systems
What other disorders are accompanied by Patau syndrome? Signs of facial deformities are by no means the only ones. The disease affects the work of almost all organ systems, causing severe congenital malformations.
- In many children, disorders of the central nervous system and visual analyzers are observed. Possible hydrocephalus, giloprochancephaly, dysginesis of the corpus callosum, as well as the formation of spinal hernias. Possible complications include deafness, congenital cataracts, retinal dysplasia, a decrease in the number of axons in the structure of the optic nerve, which leads to serious visual impairment.
- Congenital heart defects are possible , including the open aortic duct, coarctation of the aorta, defects of the interventricular and atrial septum.
- Many babies are born with kidney defects. For example, patients are diagnosed with hydronephrosis, polycystic, as well as pathology, called the "horseshoe-shaped kidney."
- Abnormal changes in the digestive tract are possible. Their list includes the formation of Meckel's diverticulums, cystic neoplasms in the pancreatic tissues, and incomplete bowel rotation.
- The mutation affects the organs of the reproductive system. In boys, a delay in lowering the testes into the scrotum (cryptorchymis), as well as a shift in the external opening of the urethra, is possible. In newborn girls, there is often hypertrophy of the labia and clitoris, the formation of a two-horned uterus, or even the formation of two separate uterus and vagina.
- Pathology affects not only the bones of the skull, but also other structures of the skeleton. For example, in children with Patau syndrome, polydactyly (the appearance of extra fingers on the feet and hands) and syndactyly (joint of the fingers) are often observed.
- All children with this disease suffer from severe forms of physical and mental retardation.
As you can see, this chromosomal pathology has dangerous and serious consequences, so the forecasts for children are unfavorable.
Diagnostic measures
Is it possible to detect a disease such as Patau syndrome during fetal development? Diagnosis at this stage is certainly possible. As already mentioned, pathology is accompanied by the occurrence of certain symptoms during pregnancy.
As a rule, suspicions of the presence of such a mutation appear during ultrasound. The specialist may note an increase in the volume of amniotic fluid, as well as the presence of abnormalities in the anatomical structure of the skeleton, the absence of hair in the fetus, low fetal body weight, etc.
In the future, genetic studies of hereditary material are carried out, because, as you know, the karyotype of a patient with Patau syndrome differs from normal. The following tests are informative.
- Amniocentesis - abstraction and further analysis of amniotic fluid.
- Cordocentesis - the essence of the technique is to obtain cord blood samples with further laboratory testing.
- Chorionic villus biopsy is a procedure that involves the collection of villi with a special probe. This test is prescribed for women with suspected Down syndrome, Patau and other chromosomal mutations.
It is worth noting that such studies are fraught with risk (for example, there is a likelihood of losing a child). After the baby is born, the diagnosis is confirmed after examination by a neonatologist or pediatrician.
Is there an effective treatment?
You already know what Patau syndrome is. The karyotype of a child with such a diagnosis is changed that affects the structure and functioning of the whole organism. Unfortunately, the possibilities for therapy are very limited. Surgery is sometimes performed to correct anatomical abnormalities (for example, facial clefts).
The child should be constantly monitored by a pediatric cardiologist, neurologist, ophthalmologist, urologist, ENT specialist, orthopedist, geneticist and other specialists. The baby needs to provide good care and good nutrition. Depending on the presence of certain disorders, symptomatic therapy is performed.
Predictions for small patients
To date, Patau syndrome is considered extremely dangerous. It is impossible to change the karyotype of a child and forecasts for children are extremely unfavorable. Very often, pregnancy ends in a miscarriage.
If the baby is still born, then, according to statistics, it rarely lives up to one year. Only in some developed countries do doctors and parents have the opportunity to extend the life of a child up to 4-5 years. Unfortunately, today medicine cannot offer effective methods of prevention or treatment.