The cytogenetic analyses of the abortus material provide valuable information about the recurence risks and possible therapies for the couples with recurrent spontaneous abortions
3. It has been reported that there was no statistically significant difference in cytogenetic abnormality frequencies of five different racial groups among the populations including 1000 cases. In the present study, it has been concluded that the variation of the chromosomal abnormality frequencies in cytogenetic analyses of abortus material could be due to the differences of applied methods in selected tissues rather than the biological variations in the study groups
5. Although our study group is small, the chromosomal abnormality incidence of our study (45.5%) seems to be compatible with literature. However, the tissue culture failure incidence of this study (56%) is higher than the reported incidences (10-40%). This shortcoming has been gradually diminished by the improvement of the tissue procument and transportation conditions for culture. We developed a protocol with Obstetrics and Gynecology and Pathology departments to maintain rapid transportation of the viable abortus materials containing placenta without using any fixative agent in sterile tissue containers. After first evaluation and tissue culture procedure with synchronous touch preparation, it had been referred to Department of Pathology for pathologic examination. So, we could provide a satisfactory data about any abortus including natural history, cytogenetic and pathologic findings.
The recent studies on the recurrent spontaneous abortions have revealed that the frequencies of the normal embryonic karyotypes were associated with previous number of the spontanous abortions. They have implicated that the previous pregnancies with normal embryonic karyotype might be an indicator for an abortus and the frequency of the liveborn following an aneuploid abortion was higher than the liveborn following euploid one 6,7. Although our data is not still available for this kind of analysis, this finding is important point for genetic counseling.
Cytogenetic analyses has revealed no significantly difference in chromosomal abnormality ratios of abortus materials between the women groups with and without spontaneous recurrent abortions 8. Studies involving couples with repeated abortus revealed that incidences of chromosomal anomalies, mainly balanced chromosomal rearrangements, were between 3.39-6.56% 9,10,11. Chromosomal anomalies in abortus materials were reported to be present in more than 50% of cases 1. Rates of spontan abortus due to reproductive problems were higher than congenital malformations. But, most of the aborted fetuses are composed of malformed and/or defective fetuses. Although sequences of spontan abortus and malformed babies are different, results including environmental factors obtained from spontan abortus cases have important place in evaluation of malformations 12. In the light of these accumulated data, our studies on abortus materials are in progress as a comprehensive epidemiological study involving incidences of anomalies and contributing etiological factors.
Although FISH analysis of common aneuploidies with uncultured material has potential for diagnosis, confirmation of these findings with standart cytogenetic techniques is important for prevention of misdiagnosis of the structural chromosomal abnormalities 13. Aneuploidies observed about 50% of spontan abortus cases are one of the main reasons to cause miscarriage 14. In total of 10 cases with chromosomal abnormalities presented in this study, except one mosaic case, aneuploidies determined with interphase FISH method were confirmed with standart cytogenetic methods. Discordance observed in the mosaic case karyotyped as 46,XX/92,XXXX by cytogenetic method mighy be due to two main reasons. Either low level of mosaicism may not be detected with FISH method or aneuploidy might be a result of in vitro conditions. Second explanation might be more reasonable since mosaicism determined cytogenetically was about 20% in tetraploidic line and this kind of anomalies are frequently observed as artifacts in long term cultured cells. In our study, 8 of 12 cases with normal karyotype were determined to be female. This finding might be partially due to overproduction of maternal tissues.
When evaluating spontan abortus cases, results obtained from aborted materials are vitally important for couples with repeated spontan abortus. These results may help to direct risk of abortus in the future and possible treatment approachs as well as they provide important data in terms of epidemiology of congenital malformations 3,6,12. Most commonly encountered failure reasons in cytogenetic analyses, which are the basic methodology used in studying aborted materials, are failure of tissue culture and overproduction of maternal originated female karyotypes which does not reflect fetuses 4. Rate of cases with abnormal karyotypes obtained from materials of aborted cases is somehow related with methodology rather than differences due to population. Therefore optimized standart methodology and protocol is necessary to obtain useful information from these studies. In the present study, we aimed at determining chromosomal anomalies constituting most of the aneuploidies under conditions where culture failure is observed by synchronized cultures with FISH preparations where related probes utilized to obtain supportive data.
In the light of accumulated data and findings of the present study, to minimize culture failure of aborted materials in cytogenetic analyses, there must be a tight colloboration between the departmens of Obstetrics and Gynecology and Pathology with the Department of Genetics. With this approach, supportive data will be accumulated and may be utilized for future epidemiological studies by concurrent FISH preparations and culture set up.
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