Preimplantation genetic diagnosis#Polar body biopsy

Polar body diagnosis (PBD ) provides, in an artificial insemination ( ICSI ) is a genetic investigation of the extracted egg. In this study, it is a prefertilisation that ie the oocyte prior to the completion of fertilization, takes place before the formation of the zygote. This diagnosis is in some countries such as Austria, where preimplantation genetic diagnosis is forbidden, nor permitted.

Method

Through in vitro fertilization, the egg is fertilized outside the body. Even before the merger of the maternal and paternal Vorkernes, the two polar bodies are removed and examined for human genetic usual. Within this short time frame - which was related to the original ban of preimplantation genetic diagnosis ( PGD) - can be carried out until the merger of the pronuclei ( syngamy ) and thus the formation of an embryo following investigations:

• Chromosome set maldistribution
• Translocations
• Segregation evidence of maternally inherited monogenic disease by PCR

When findings are unremarkable conclusion fertilization and the first cell divisions can wait, and the resulting embryo can be implanted in the uterus.

The investigation of the chromosome set is carried out in particular with regard to the increasing maternal age with aneuploidy (eg, trisomy 21). In monogenic diseases, the detection of disease-causing allele in the polar body can give information about whether the healthy allele is present in the oocyte. This presupposes, however, that the genetic disease to be investigated is known in the mother. Thus, genetic disorders can be detected after pating metallic inheritance only maternal inherited dominant and X-linked; can in recessive - when a sickening allele is known the Father - either loaded onto a 25 % risk or closed with respect to all those heterozygous allele oocytes are discarded. Since only the maternal genome is detectable are all paternal factors not evident. In this respect, the PID of the PKD is technologically superior in many ways.

Use and safety

The polar body has been promoted in Germany mainly because the Embryo Protection Act has been allowed only very limited pre-implantation diagnosis. A review from the year 2008 shows that in women who have an increased aneuploidy due to their seniority, the Einnistungswahrscheinlichkeit of transferred embryos slightly increases and the rate of miscarriage decreases after a polar body. A significant increase in the birth rate could not be proven.

By December 2011, the legal position regarding PGD in Germany has changed, so this is essentially allowed for those indications. Science will show to what extent yet medically reasoned advantages of polar body diagnosis relate to the pre-implantation diagnosis.