PubMed · 244555
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H Takahara, I Hisazumi, T Hiasa, E Okamoto, K Ohara. 1977. growth.. https://pubmed.ncbi.nlm.nih.gov/244555/
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Since the beginning of in vitro fertilization (IVF), basic research has provided insight in the field of human reproduction, especially in genetics. Indeed, the contribution of chromosomal abnormalities to oocyte disorders and impaired embryonic development is now well known. Of oocytes that fail to fertilize after in vitro insemination, 26.5% have been found to be abnormal, with 13.3% showing hypohaploidy, 8.1% hyperhaploidy, 1.6% structural abnormalities and 3.5% diploidy. The total incidence of abnormalities seems to be correlated with the fertility status of the woman. It is higher in oocytes from women with tubal or unexplained infertility than in those from women whose husband's infertility is the sole cause of infertility in the couple. Although few oocytes recovered during natural cycles have been studied, gonadotropins, which are widely used to stimulate follicle growth and ovulation, do not increase the risk of abnormalities. The effect of maternal age on fetal aneuploidy, well documented at birth, has not been unambiguously shown to result from an increase in the frequency of aneuploid oocytes. Intra- and extra-follicular influences (perifollicular microvasculature, oxygenation, and the presence of residues from cigarette smoke) may disturb maturation, leading to immaturity and aneuploidy. Thus, oocyte meiosis is very sensitive to endogenous and exogenous factors that could result in oocytes with chromosomal abnormalities and therefore, abnormal zygotes.
INTRODUCTION: The purpose was to detect chromosome abnormalities in dysmorphic and mentally retarded individuals with normal karyotypes by means of comparative genomic hybridisation (CGH). MATERIAL AND METHODS: One hundred and forty-four individuals with normal karyotype underwent CGH analysis with a new detection technique where fixed limits are replaced by dynamic standard reference intervals. This method provides improved resolution and thereby detects minor chromosome abnormalities. RESULTS: Fifteen minor abnormalities (10%) and one trisomy 9 mosaic were found. Eleven were interstitial deletions or duplications, which cannot be detected by screening with other cytogenetic techniques. Three were terminal deletions or duplications and one was a terminal unbalanced translocation. DISCUSSION: CGH analysis with dynamic standard reference intervals is a new objective and quantitative method, which is suitable for screening for small chromosome abnormalities that can not be detected by conventional chromosome analysis. The method is recommended for use in the investigation of dysmorphic and mentally retarded individuals, in whom abnormalities are not found by ordinary karyotyping.
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