Peri-ovulatory putrescine to reduce aneuploid conceptions
نویسندگان
چکیده
experience diminished fertility, increased risk of miscarriages and congenital birth defects in their late 30s and early 40s, 10-15 years before reaching menopause. Egg aneuploidy (having an incorrect number of chromosomes) is the most important etiology for these reproductive problems in older women. Science correspondent Jon Cohen wrote a News piece in 2002 [1] on the quest to understand the mechanisms of maternal aging-related aneuploidies in humans, which is still applicable today. Although we have made impressive progress in understanding how aneuploidies arise, we know little about providing medical interventions to reduce them. " My Holy Grail is to deliver some sort of aneuploidy-reduction pill, … " , Dr. Terry Hassold, a leading geneticist in the field, is quoted as saying. Our recent study [2] may be a step towards developing such a pill. Aneuploid eggs result in aneuploid conceptions, most of which are lost either prior to clinical recognition of pregnancies or by miscarriages. The small proportion that survive inevitably carry major birth defects. Accurate egg aneuploidy rates in the general population are not known, but numerous analyses of IVF samples have revealed staggeringly high rates. Notably, a recent study of more than 20,000 IVF eggs revealed significant age-related aneuploidies, reaching >40% in the 40 year old age group [3]. Furthermore, this study [3] employs fluorescence in situ hybridization of polar bodies and is therefore limited in the number of chromosomes (five) that can be analyzed simultaneously. The true aneuploidy rates in older women, considering all 23 chromosomes, would be expected to be much higher. This unusually high egg aneuploidy rate in humans is likely due to a combination of our longevity and the peculiar oogenesis (the process of generating eggs) in all vertebrates including humans. Unlike vertebrate males that continuously generate mature sperm from germ line stem cells through adulthood, in vertebrates oogenesis begins during the embryonic stage when germ line stem cells initiate meiosis and develop into primary oocytes. By birth, the females have developed a finite number of primary oocytes arrested in meiotic prophase that comprises their lifetime egg supply. The prophase oocytes contain chromosome bivalents each Editorial having four chromatids linked together by a combination of sister chromotid cohesion and non-sister cross-over (Figure 1), with this linkage persisting for decades in women. During ovulation the two sister chromatids are segregated to the same cell (egg or 1st polar body) in a process called oocyte maturation; …
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