ABSTRACT
Cytogenetic study of reproductive wastage is an important aspect in deter-mining the genetic background of early embryogenesis. Approximately 15 to 20% of all pregnancies in humans are terminated as recurrent spontaneous abortions [RSAs]. The aim of this study was to detect chromosome abnormalities in couples with RSAs and to compare our results with those reported previously. In this retrospective study, the pattern of chromosomal aberrations was evaluated during a six-year period from 2005 to 2011. The population under study was 728 couples who attended genetic counseling services for their RSAs at Pardis Clinical and Genetics Laboratory, Mashhad, Iran. In this study, about 11.7% of couples were carriers of chromosomal aberrations. The majority of abnormalities were found in couples with history of abortion, without stillbirth or livebirth. Balanced reciprocal translocations, Robertsonian translocations, inversions and sex chromosome aneuploidy were seen in these cases. Balanced reciprocal translocations were the most frequent chromosomal anomalies [62.7%] detected in current study. These findings suggest that chromosomal abnormalities can be one of the important causes of RSAs. In addition, cytogenetic study of families who experienced RSAs may prevent unnecessary treatment if RSA are caused by chromosomal abnormalities. The results of cytogenetic studies of RSA cases will provide a standard protocol for the genetic counselors in order to follow up and to help these families
Subject(s)
Humans , Male , Female , Abortion, Spontaneous , Family Characteristics , Cytogenetic Analysis , Retrospective StudiesABSTRACT
Reciprocal translocations represent one of the most common structural rearrangements observed in humans. Estimates of the population frequency range from 1/673 to 1/1000. We have described two novel balanced translocations in two unrelated families who experienced Recurrent Spontaneous Abortions [RSA] following their separate non-consanguineous marriages. Initial cytogenetic studies were performed on cultured blood cells. High resolution GTG-banding analysis using cytovision software performed on their chromosomes revealed a novel balanced translocation t[8;11][p23;q21] in a brother [45 years] and his sister [27 years] in one family. The second novel balanced translocation t[6;16][q26;p12] was observed in a consanguineous couple with 4 RSA. These two families have an increased risk of having children with unbalanced karyotypes or RSA, because of incorrect chromosomal segregation during meiosis
ABSTRACT
Autosomal recessive spinal muscular atrophy is a disease resulting from homozygous absence of SMN1 gene in approximately 94% of SMA patients. To identify patients who retained a single SMN1 copy, SMN1 dosage analysis was performed by quantitative Real-time PCR using SYBR green dye. SMN1 dosage analysis results were utilized to identify carriers before offering prenatal diagnosis. Carrier testing was performed for 150 individuals. Copy number of the SMN1 gene was determined by the comparative threshold cycle [Ct] method and human serum albumin gene was used as a reference. Analysis of 150 DNA samples with quantitative PCR determined the number of SMN1 gene copies. Of these, 50 [33.33%] cases had one SMN1 gene copy, 87 [58%] had two copies and 13 [8.66%] did not have any copies of SMN1. The homozygous SMN1 deletion ratio was 0.00 and deletion of one copy of SMN1 gene ratio ranged from 0.3 to 0.58. This report demonstrates modification of risk estimation for the diagnosis and detection of SMA carriers by accurate determination of SMN1 copy number. SMN1 copy number analysis is an important parameter for identification of couples at risk of having children affected with SMA. It also reduces unwarranted prenatal diagnosis for SMA. Furthermore, the dosage analysis might be useful for the counseling of clinically suspected SMA patients with negative diagnostic SMA tests