Novel balanced chromosomal translocations in couple with recurrent spontaneous abortions

سال انتشار: 1397
نوع سند: مقاله کنفرانسی
زبان: انگلیسی
مشاهده: 307

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شناسه ملی سند علمی:

CCRMED02_071

تاریخ نمایه سازی: 11 اردیبهشت 1398

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INTRODUCTIONRecurrent spontaneous abortion (RSA) is significant reproductive problem and defined as three or more consecutive pregnancy losses before the 20th weeks of gestation.the prevalence of RSA is approximately 1–5% of conceptions (1).The cause being multifactorial such as anatomic malformations, chromosomal disorders, endocrine disorders, coagulation diseases, infections, or autoimmune diseases(2).Fetal aneuploidy is well known that causes approximately 50% of sporadic (nonrecurrent) miscarriages before the 10th week of gestation and the errors during this process lead to aneuploidy(3). Balanced translocations are frequent structural chromosomal rearrangements with population frequency rates are between 1/673 and 1/1000(4).Here male with balanced translocations is clinically normal; however, he has an increased risk of having progeny with unbalanced karyotypes with interference in the meiotic segregation of their abnormal chromosomes.MATERIALS AND METHODSChromosome preparations was made by phytohemagglutinin -stimulated peripheral blood lymphocyte cultures and methotrexate synchronized culture, of the couple-both the male and the female partner. Lymphocyte culturing and GTG-banding were performed following standard protocols as described by the AGT cytogenetics laboratory manual(5). Karyotypes were described according to the International System for Cytogenetic Nomenclature(6).CASE REPORTwe are reporting the history of RSAs in in 36-year-old man and 35-year-old woman with an unknown cause. Reproductive history of the female revealed five intra-uterine fetal deaths (IUFD) before the 12th week of pregnancy. The cause and genetic status of the miscarriages were not known. The results showed balanced chromosomal translocations between the long arm of chromosome 13 and the short arm of chromosome 18 only for the male partner with clinically normal phenotype.DISCUSSIONAccording to studies the prevalence of chromosomal abnormalities, is approximately 8% in infertility and pregnancy losses. RSA is historically defined as three or more consecutive pregnancy losses before 20–22 weeks of gestation. However, some investigators feel that even two spontaneous losses constitute recurrent miscarriage and need evaluations. In patient with history of two miscarriages, the subsequent risk of pregnancy loss rises to about 25%, whereas three abortions raise the risk of fourth miscarriage to 33%.Although the cause is unknown in many instances, the parental chromosomal abnormality is one of the possible causes for recurrence of miscarriages within the first months of pregnancy.The present study thus reported novel balanced reciprocal translocations that could result in generation of unbalanced gametes due to meiotic errors associated with first trimester recurrent pregnancy losses. Cytogenetic analysis, therefore, should be mandatory for all the couples with reproductive failures. Thus, the carriers of such abnormalities should be informed about the risk of the birth defects in their offspring due to de novo submicroscopic rearrangements. Adequate genetic counseling strategies should also be offered which could allow the parents/couples to make an informed reproductive decision regarding subsequent pregnancies.