الفهرس 
Review of literature
Chromosomal aberrationsOnly 14 pages are availabe for public view
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Abstract
The product of a combination of cytogenetics and molecular biology, the technique of fluorescence in situ hybridization (FISH), has increased the resolution and application of traditional cytogenetics. Currently, FISH is widely used to assess the localization of genetic elements in tissues, nuclei of cultured cells and spreads of metaphase chromosomes. This work aims at using the recently applied FISH technique in the field of molecular cytogenetics for: a) Characterization of sex chromosomes aberrations among cases of ambiguous genitalia or intersex and cases of pubertal failure as amenorrhea b) For prenatal diagnosis of Down syndrome among high risk pregnant women. Methods used in this study were in the form of: traditional Karyotyping used for both amniotic fliud and peripheral blood samples for complete chromosomal analysis. Also FISH technique was applied on both types of samples for detection of chromosomal abnormalities by using commerchially avaliable DNA specific probes Ls1 21 probe for chromosome 21 and CEP probe for X/Y chromosomes. Routine hormonal assays was done to cases of sex chromosomes disorders and ambiguous genitalia for confirmation of their sex determanation. Subjects included in this work are of two categories. A) Seven pregnant woman at high risk values of having DS fetuses, their age ranged from 25 to 42 years old, includes: 3 cases with a history of having affected offsprings with DS, 2 cases with advanced age ( more than 35 years), and 2 cases at high risk due to their triple test results. They were subjected to: 1 Complete history of previous deliveries. 2 Triple screen detection of AFP, HCG and E2. 3 Amniotic fluid samples are tested for chromosome 21 by using fluorescence in situ hybridization (FISH) technique. B) Twelve cases presenting with abnormal genitalia or sex chromosome disorders for sex determination, their age ranged from 1 month to 26 years old., includes: 9 cases with ambiguous genitalia, 2 cases with amenorrhea and 1 case with infertility. They were subjected to: 1 Complete family history taking and physical examination. 2 Conventional cytogenetic analysis, karyotyping by using computerized cytogenetic analyzing system. 3 Detection of X,Y chromosomes by using fluorescence in situ hybridization (FISH) technique. 4 Hormonal assay In the present study FISH technique was used for prenatal diagnosis of Down syndrome as well as fetal sexing by means of specific probes for 21, X and Y chromosomes in cases of high risk women. This risk factor was obtained via a riskcalculation software that calculates multiples of the median data using paramters as maternal age and triple test. Also women that had previous delivers of Down syndrom were considered to be high risk cases. Amniocentesis was performed on 7 pregnant women with a high risk of having Down syndrome fetuses. Five cases had undergone both interphase FISH and karyotyping analysis while the other 2 had undergone interphase FISH analysis only. We could diagnose Down Syndrome fetus in only one case presented with high risk value calculated by her triple test results. All the other 6 cases showed negative test results for Down syndrome which was confirmed lateron after delivery. Traditional karyotyping is a time consuming technique it takes form 35 weeks if compared to FISH which is a rapid, sensitive and reliable one. When performed on the uncultured amniotic fluid samples it gives a fast tool for prenatal diagnosis in only 24 hours. This work included also another 12 cases suspected of having sex chromosome disorders and ambiguous genitalia. Of them, 9 cases presented with ambiguous genitalia, 2 with 1ry Amenorrhea and one with 1ry infertility. For these cases cytogenetic studies was done by traditional karyotyping and FISH technique using CEP X/Y probes in addition to relevant hormonal studies. from the study, it was found that six cases had a final gender diagnosis different from their primary one.