Preimplantation genetic diagnosis

Abstract

Pre‐implantation genetic diagnosis (PGD) is generally defined as the testing of pre‐implantation stage embryos or oocytes for genetic defects. It has been developed for couples whose potential offspring are at risk of severe Mendelian disorders, structural chromosome abnormalities or mitochondrial disorders. Pre‐implantation embryo diagnosis requires in vitro fertilization, embryo biopsy and either using fluorescent in situ hybridization or polymerase chain reaction at the single cell level. Therefore, it is a complex procedure which requires much experience. Aneuploidy screening to improve medically assisted reproduction (in vitro fertilization/intracytoplasmic sperm injection) is a variant type of PGD. The past, present and future of this development are strongly related to the natural occurrence of chromosomal mosaicism in the pre‐implantation embryo. PGD should be included in each reproductive health care programme. It is recognized as an important alternative to pre‐natal diagnosis. However, diagnosis from a single cell remains a technically challenging procedure, and the risk of misdiagnosis cannot be eliminated. An ethical discussion of the question of whether PGD is acceptable at all–the ‘desirability question’–is a rearguard action. Discussion must primarily focus on the conditions of exercising due caution in and the dynamics of PGD.

What Is the Role of Genetic Testing in Movement Disorders Practice?

“…Pre-implantation testing is a complex procedure that allows selection of embryos without the disease-causing mutation or repeat expansion. This can also be performed without communicating the results of the test to the parents in case they do not wish to be informed whether or not they are at-risk carriers (nondisclosure testing) [20][21][22]. An incomplete compilation of other genetic movement disorders is presented.…”

Karyomapping and how is it improving preimplantation genetics?

“…PGS (or PGD-A) refers to non-targeted technologies that detect chromosome abnormalities (principally aneuploidy), whereas PGD generally pertains to the detection of single gene disorders, translocations and Human Leukocyte Antigen (HLA) matching for immunological compatibility testing [9][10][11]. This technology was applied clinically for the first time for the treatment of Fanconi anaemia (FA) by HLA matching [12] and has since been shown in many clinical studies that PGD in combination with HLA typing is an effective therapeutic tool for treatment of an affected sibling [13][14][15][16].…”

Management of Inherited Bleeding Disorders in Pregnancy

“…Appendix III: Methods for prenatal diagnosis [228][229][230][231][232][233][234][235][236][237][238] Investigation/ procedure Timing: weeks of gestation Important information Recommendations Noninvasive PND for fetal sex determination > 9 PCR analysis of cffDNA, originating from the placenta and present in maternal blood, permits noninvasive determination of fetal sex early in pregnancy. Overall sensitivity of 95% and specificity of 98% are reported.…”

“…Genetic analysis performed prior to implantation of IVFgenerated embryo PGD, 233 an IVF-based process, is an option for couples at risk of transmitting a heritable disorder to their offspring:…”