الفهرس 
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Abstract
Infertility is a universal issue, affecting millions of men and women in both developed and developing areas of the world. Genetic causes may be identified in a large proportion of infertile couples. In about 15% of male and 10% of female infertile subject genetic abnormalities could be present, including chromosome aberrations and single gene mutations. Recent advances in the field of reproductive medicine may allow for a select group of infertile couples to conceive and bear offspring by utilizing assisted reproductive techniques (ART).
Assisted reproductive technology (ART) is the application of laboratory or clinical techniques to gametes and/or embryos for the purposes of reproduction. The ART techniques include artificial insemination, super-ovulation, in vitro fertilization, embryo collection, embryo transfer, embryo cryopreservation, cloning, and pre-implantation genetic diagnosis.
Rapid advances in techniques to manipulate embryos in the laboratory have permitted screening of embryos for genetic defects. Preimplantation genetic diagnosis is an alternative to prenatal diagnosis for the detection of genetic disorders in couples at risk of transmitting a genetic condition to their offspring. Preimplantation screening has been proposed to improve the effectiveness of IVF in women of advanced maternal age or with recurrent miscarriage or implantation failure, but this approach has led to conflicting results.
ART may interfere with the process of imprinting and epigenetic reprogramming in gametes and preimplantation embryos and lead to epigenetic defects. Data from animal studies and human epidemiological studies suggest a higher incidence of imprinting defects after ART, but this is still controversial.
As researchers and scientists note the sudden decline in male reproductive potential worldwide, many have focused their attention on male-factor defects. Although much remains unknown about human spermatozoa and its pathological and physiological effects on reproductive function, recent advances in proteomic techniques have provided insight into sperm function and dysfunction.
Because of their regenerative potential, stem cells are ideal therapeutic agents for defective conditions such as male infertility. Gametes may be created through the differentiation of currently established hESC lines and are herein referred to as ES-cell-derived gametes. It may theoretically be possible to create ‘customized gametes’ by using nuclear transfer technology to derive ES cells cloned from an embryo. These cloned ES cells may differentiate into either sperm or ova which contains a haploid set of genes from the individual.
Conclusion: PGD is an alternative to prenatal diagnosis for the detection of genetic disorders in couples at risk of transmitting a genetic condition to their offspring. The efforts to improve the success rate of PGD involve all steps in the procedure. The most promising method is CGH, which can accurately determine total or partial aneusomy by loss or gains of DNA, using a combination of PCR and FISH technology.