Patau syndrome, or trisomy of chromosome 13 syndrome, a severe genetic disease where in the karyotype (chromosome set), there is an extra copy of chromosome 13.
About 1 in 7000-10000 babies are born with the defect. Gene mutation occurs in both boys and girls equally.
Patau syndrome Causes
It is found that the cause Patau syndrome, in most cases, is tripling of chromosome 13, that is, in each cell there is not two (normal), and three copies of chromosome thirteenth. In very rare cases, only a part of the body's cells have an extra copy. This so-called Mosaic Patau syndrome.
Another cause of the disease - a translocation (rearrangement) of chromosomes as part of the 13 chromosomes before or at the moment of conception tied to other non-homologous chromosome. As a result of such adjustment in patients along with two copies of chromosome 13, an additional material therefrom, which is connected to the other chromosome. There is a partial trisomy of chromosome 13, where the physical signs of the syndrome are somewhat different from the typical clinical picture.
As a rule, Patau syndrome is not inherited and occurs randomly in the formation of sperm and eggs. If cell division error called nondisjunction, this leads to the appearance of gametes with the wrong number of chromosomes. When these abnormal sperm and eggs are involved in the genetic structure of the child, he gets an extra chromosome 13 in all cells of the body. Mosaicism of this syndrome are not inherited and occurs as a random crash during cell division at the initial stage of embryo development.
The disease may be inherited in the case of balanced translocation when a healthy person is altered genetic material between the thirteenth and other chromosomes. Persons who are carriers are at risk of having children with this genetic disorder, and although they have no signs of trisomy of chromosome 13.
The clinical picture
All children with Patau syndrome are severe malformations of the skull, brain, internal organs and the musculoskeletal system.
The characteristic features of the disease include:
- Poorly developed brain and facial bones of the skull;
- Trigonocephaly (severe narrowing of the frontal part of the skull, and a sharp increase in the occipital);
- Changes in the structure of the hands and feet;
- Symmetrical polydactyl (possible, but there is not always);
- Narrowing the eye slits, and the proximity of their sockets;
- The shortening of the neck;
- The absence of the iris or eyeball (sometimes);
- Deformation and incorrect placement of ears;
- Cleft lip and palate;
- Ceasing bridge etc..
In infants with Patau syndrome is underdeveloped digestive system and the basic brain structures of the CNS. Heavy malformations observed in the cardiovascular system - heart defects partitions and large blood vessels. Suffers urogenital system: cryptorchidism (undescended testicles), two-horned uterus, hypoplastic external genitalia. Sometimes there is no back wall of the urethra and kidneys greatly increased in size, and have at their cortex cyst.
Patau Syndrome Diagnosis
Prenatal diagnosis of chromosomal diseases, including Patau syndrome, is the same. The first stage of the screening includes ultrasound examination and determination of biochemical markers (PAPP-A, beta-hCG, and others.). Based on the data calculated risk of having a child with a genetic disease.
Pregnant women who were at risk, the following methods are invasive prenatal diagnosis:
- 8-12 weeks - chorionic villus sampling (taking a sample of cells of the villi and check for defects);
- 14-18 weeks - amniocentesis (puncture of the amniotic membrane to obtain amniotic fluid for subsequent laboratory analysis);
- 20 weeks or more - cordocentesis (umbilical cord blood analysis).
The obtained materials are searched trisomy chromosome 13 by KF-PCR (quantitative fluorescent polymerase chain reaction) or karyotype with differential staining of chromosomes.
If prenatal diagnosis of Patau syndrome was not carried out, to identify a chromosomal anomaly can be based on clinical signs. However, to confirm a diagnosis of needs analysis to determine the chromosome set of the newborn.
Infants with established or suspected hereditary disease require careful examination of the complex, which is aimed at identifying severe malformations (neurosonography, renal ultrasound and abdominal echocardiography, and others.).
Treatment and prognosis
Specific treatment Patau syndrome, for obvious reasons (failures in the genetic apparatus), no. For the correction of congenital surgeries carried out, and to maintain the normal functioning of organs and systems prescribe strengthening therapy (multivitamin complexes, dietary supplements and drugs to improve immunity).
The prognosis of this disease is poor. The majority of children with Patau syndrome die within the first months of life, but sometimes living to year. This is due to a high degree of severity of congenital malformations of the internal organs. In rare cases, patients live 3-5 years while remaining totally disabled and having a sharp disturbances in psychomotor development.