molecular detection and genotypic characterization of toxoplasma gondii in paraffin-embedded fetoplacental tissues of women with recurrent spontaneous abortion

background: congenital toxoplasmosis is an important cause of spontaneous abortion worldwide. however, there is limited information on detection and genotypic characterization of t. gondii in women with recurrent spontaneous abortion (rsa). the aim of this study is molecular detection and genotypic characterization of t. gondii in formalin-fixed, paraffin-embedded fetoplacental tissues (ffpts) of women with rsa referred to the avicenna research institute in tehran, iran. materials and methods: this diagnostic research was undertaken on 210 formalin-fixed, paraffin-embedded fetoplacental tissues of women with rsa. the information of the patients was collected from the archives of avicenna research institute in tehran, iran. after dna extraction, the presence of t. gondii was examined by nested polymerase chain reaction targeting the gra6 gene. genotyping was performed on positive samples using pcr-rflp technique targeting the gra6 and sag3 genes. also, sequencing was conducted on two gra6 positive samples. results: t. gondii dna was detected in 3.8% (8/210) of the samples. genotyping showed that all positive samples were belonged to type iii of t. gondii genotype. sequencing of two genomic dna of gra6 gene revealed 99% similarity with each other and 99–100% similarity with t. gondii sequences deposited in genbank. six patients had a history of more than three previous abortions; one patient had a healthy girl and another patient had two previous abortions. abortions were occurred in the first trimester of pregnancy in seven patients and in the second trimester of pregnancy in one patient. conclusion: the results of this study indicated that genotype iii is the predominant type of t. gondii in women with rsa in tehran, iran. also, our findings suggest that toxoplasmosis may play a role in the pathogenesis of rsa. however, further studies are needed to elucidate a clear relationship between t. gondii infection and rsa.