A Decade of Molecular Preimplantation Genetic Diagnosis of 350 Blastomeres for Beta-Thalassemia Combined with HLA Typing, Aneuploidy Screening and Sex Selection in Iran

Background: Preimplantation genetic diagnosis (PGD) has been developed to detect genetic disorders before pregnancy which is usually done on blastomeres biopsied from 8-cell stage embryos obtained from in vitro fertilization method (IVF).Here we report molecular PGD results for diagnosing of beta thalassemia (beta-thal) which are usually accompanied with evaluating chromosomal aneuploidies, HLA typing and sex selection.Methods: In this study, haplotype analysis was performed using short tandem repeats (STRs) in a multiplex nested PCR and the causative mutation was detected by Sanger sequencing.Results: We have performed PGDs on 350 blastomeres from 55 carrier couples; 142 blastomeres for beta-thal only, 75 for beta-thal and HLA typing, 76 for beta-thal in combination with sex selection, and 57 for beta-thal and aneuploidy screening. 150 blastomeres were transferable, 15 pregnancies were happened, and 11 babies born.We used 6 markers for beta-thal, 36 for aneuploidy screening, 32 for sex selection, and 35 for HLA typing. To our knowledge combining all these markers together and the number of STR markers are much more than any other studies which have ever done.Conclusions: PGD is a powerful diagnostic tool for carrier couples who desire to have a healthy child and wish to avoid medical abortion.

Preimplantation Genetic Diagnosis in Hereditary Hearing Impairment

Sensorineural hearing impairment is a common sensory deficit in children and more than 50% of these cases are caused by genetic etiologies, that is, hereditary hearing impairment (HHI). Recent advances in genomic medicine have revolutionized the diagnostics of, and counseling for, HHI, including preimplantation genetic diagnosis (PGD), thus providing parents-to-be with better reproductive choices. Over the past decade, we have performed PGD using the amplification refractory mutation system quantitative polymerase chain reaction (ARMS-qPCR) technique in 11 couples with a history of HHI, namely eight with GJB2 variants, one with OTOF variants, one with SLC26A4 variants, and one with an MITF variant. We demonstrated that PGD can be successfully applied to HHI of different inheritance modes, namely autosomal dominant or recessive, and phenotypes, namely syndromic or non-syndromic HHI. However, certain ethical concerns warrant scrutiny before PGD can be widely applied to at-risk couples with a history of HHI.

Pre-implantation Screening and Diagnosis

Through cellular biopsy of a developing embryo, genetic testing can be performed as part of the embryo selection phase of an in vitro fertilization (IVF) cycle. Preimplantation genetic screening (PGS) and preimplantation genetic diagnosis (PGD) allow embryos to be tested for genetic conditions on a chromosome and gene level, respectively, prior to implantation in the uterus and prior to pregnancy. Included in this review are indications for PGS and PGD, the biopsy and diagnostic methods that are most frequently utilized, advances in recent non-invasive technologies, and potential impacts that PGS/PGD and IVF may have on developing embryos. This review contains 5 figures, 1 table, and 53 references. Keywords: Preimplantation genetic diagnosis, preimplantation genetic screening, blastocyst biopsy, blastomere biopsy, advances in PGS/PGD, indications for PGS/PGD, non-invasive embryo biopsy, infertility