Patau's syndrome

Patau's syndrome, or syndrome of a trisomy of a chromosome 13, represents a serious genetic illness at which in a karyotype (chromosomal complement) there is an additional copy of a chromosome 13.

About 1 of 7000-10000 babies is born with such defect. Genovariation occurs at boys and girls equally.

Reasons of a syndrome of Patau

It is established that, in most cases, trebling of the 13th chromosome is the reason of a syndrome of Patau, that is in each cell there are not two (norm), and three copies of the thirteenth chromosome. Seldom or never only a part of cells of an organism has the additional copy. It is a so-called mosaic syndrome of Patau.

One more cause of illness – a translocation (reorganization) of chromosomes when part 13 of a chromosome to or directly at the time of conception becomes attached to other nonhomologous chromosome. As a result of such reorganization patients along with two copies of the 13th chromosome have additional material from it which is connected to other chromosome. There is a partial trisomy of the 13th chromosome at which physical signs of a syndrome differ from a typical clinical picture a little.

As a rule, Patau's syndrome is not inherited, and arises accidentally in the course of formation of spermatozoa and ova. If at cell fission there is a mistake which is called not discrepancy, it leads to emergence of sex cells with the wrong chromosome number. When similar atypical spermatozoa and ova are involved in genetic structure of the child, he receives an additional 13th chromosome in all cells of an organism. Mosaicism of this syndrome is also not inherited and arises as accidental failure at cell fission at an initial stage of development of a germ.

The disease can be inherited in case of the balanced translocation when the healthy person bears the changed genetic material between the thirteenth and other chromosomes. The persons which are carriers enter into risk group on the birth of children with this genetic disease though and have no signs of a trisomy of a chromosome 13.

Clinical picture

All children with Patau's syndrome have heavy inborn defects of a skull, brain, internals and a musculoskeletal system.

Treat characteristic symptoms of a disease:

• Inadequately developed bones of a brain and facial skull;
• Trigonotsefaliya (strong narrowing of a skull in a frontal part and sharp expansion in occipital);
• The changed structure of brushes and feet;
• Symmetric polydactylism (it is possible, but arises not always);
• Narrowing of palpebral fissures and close arrangement of eye-sockets;
• Shortening of a neck;
• Lack of an iris of the eye or eyeglobe (sometimes);
• Deformation and wrong arrangement of auricles;
• Crevice of a lip and sky;
• Sticking of a nose bridge, etc.

At babies with Patau's syndrome the alimentary system and the main brain structures of TsNS is underdeveloped. Heavy malformations are observed in cardiovascular system – defects of cordial partitions and large blood vessels. The urinogenital system suffers: cryptorchism (not omission of testicles), two-horned uterus, hypoplasia of external genitals. Sometimes there is no back wall of an urethra, and kidneys are strongly increased in sizes and have cysts in the bast layer.

Diagnosis of a syndrome of Patau

Prenatal diagnosis of all chromosomal diseases including Patau's syndrome, it is identical. The first stage of screening includes an ultrasonography research and definition of biochemical markers (PAPP-A, beta HGCh, etc.). On the basis of the obtained data the risk of the birth of the child is calculated with a genetic disease.

Offer pregnant women who got into risk group the following methods of invasive prenatal diagnosis:

• 8-12 weeks – a biopsy ворсин chorion (capture of a sample of cells ворсин and their check on existence of defects);
• 14-18 weeks – amniocentesis (a puncture of an amniotic cover for receiving amniotic waters for the purpose of their subsequent laboratory research);
• 20 weeks and more – кордоцентез (the analysis of umbilical blood).

In the received materials search of a trisomy in the 13th chromosome by the KF-PTsR method (quantitative fluorescent polymerase chain reaction) or karyotyping with differential coloring of chromosomes is carried out.

If prenatal diagnosis of a syndrome of Patau was not carried out, it is possible to reveal chromosomal anomaly on the basis of clinical signs. However the analysis on definition of chromosomal complement of the newborn is necessary for confirmation of the diagnosis.

Babies with the established or estimated hereditary disease need careful comprehensive examination which is directed to detection of heavy malformations (a neyrosonografiya, ultrasonography of kidneys and abdominal organs, an echocardiography, etc.).

Treatment and forecast

Specific treatment of a syndrome of Patau, for obvious reasons (failures in the genetic device), no. For correction of inborn defects carry out operative measures, and for maintenance of normal functioning of systems and bodies appoint fortifying therapy (polyvitaminic complexes, dietary supplements and drugs for increase in level of immunity).

The forecast at this disease adverse. The bulk of children with Patau's syndrome dies in the first months of life, only sometimes living about one year. It is explained by high severity of inborn defects of internals. In rare instances patients live 3-5 years, remaining at the same time full disabled people and having sharp disturbances in psychomotor development.