Correction to: How common is germinal mosaicism that leads to premeiotic aneuploidy in the female?

The original article unfortunately contained a mistake. In the online version of the paper, the words "MII (metaphase II)-PB1 (1st polar body) complex (MII-PB1 complex)" in table 1 are incorrectly placed.

How common is germinal mosaicism that leads to premeiotic aneuploidy in the female?

Purpose: Molecular cytogenetic analysis has confirmed that a proportion of apparently meiotic aneuploidy may be present in the germ cells prior to the onset of meiosis, but there is no clear perception of its frequency. The aim of this review is to assess the evidence for premeiotic aneuploidy from a variety of sources to arrive at an estimate of its overall contribution to oocyte aneuploidy in humans.

Methods: Relevant scientific literature was covered from 1985 to 2018 by searching PubMed databases with search terms: gonadal/germinal mosaicism, ovarian mosaicism, premeiotic aneuploidy, meiosis and trisomy 21.

Functional assessment for elimination of mismatches in nuclear and whole cell extracts obtained from mouse and human blastocysts.

Preimplantation embryos may have an increased risk of having mismatches due to the rates of cell proliferation and DNA replication. Elimination of mismatches in human gametes and embryos has not been investigated. In this study we developed a sensitive functional assay to examine the repair or elimination of mismatches in both commercially available cell extracts and extracts obtained from preimplantation embryos.

Differential expression of parental alleles of BRCA1 in human preimplantation embryos.

Gene expression from both parental genomes is required for completion of embryogenesis. Differential methylation of each parental genome has been observed in mouse and human preimplantation embryos. It is possible that these differences in methylation affect the level of gene transcripts from each parental genome in early developing embryos.

The impact of mosaicism in preimplantation genetic diagnosis (PGD): approaches to PGD for dominant disorders in couples without family history.

Objectives: Mosaicism in certain dominant disorders may result in a 'non-Mendelian' transmission for the causative mutation. Preimplantation genetic diagnosis (PGD) is available for patients with inherited disorders to achieve an unaffected pregnancy. We present our experience for two female patients with different dominantly inherited autosomal disorders; neurofibromatosis type 1 (NF1) and tuberous sclerosis complex type 2 (TSC2).

MicroRNA expression and its association with DNA repair in preimplantation embryos.

Active DNA repair pathways are crucial for preserving genomic integrity and are likely among the complex mechanisms involved in the normal development of preimplantation embryos. MicroRNAs (miRNA), short non-coding RNAs, are key regulators of gene expression through the post-transcriptional and post-translational modification of mRNA. The association of miRNA expression with infertility or polycystic ovarian syndrome has been widely investigated; however, there are limited data regarding the importance of miRNA regulation in DNA repair during preimplantation embryo development.

Telomere length in human blastocysts.

This is a retrospective study aiming to assess telomere length in human embryos 4 days post fertilization and to determine whether it is correlated to chromosomal ploidy, embryo developmental rate and patient age. Embryos were donated from patients undergoing treatment in the assisted conception unit. Seven couples took part, generating 35 embryos consisting of 1130 cells.

Investigation of gene expression profiles before and after embryonic genome activation and assessment of functional pathways at the human metaphase II oocyte and blastocyst stage.

Objective: To compare the oocyte versus the blastocyst transcriptome and provide data on molecular pathways before and after embryonic genome activation.

Design: Prospective laboratory research study.

Setting: An IVF clinic and a specialist preimplantation genetics laboratory.

Preimplantation genetic diagnosis: recent triumphs and remaining challenges.

Over the last 20 years, preimplantation genetic diagnosis (PGD) has changed from being an experimental procedure to one that is carried out in specialized diagnostic centers worldwide. Genetic awareness and the rapid identification of germline mutations or chromosomal abnormalities enable individuals to know their risk of transmitting a genetic disease before they have children. This has created a demand for PGD from couples who wish to avoid terminations of affected pregnancies.

Preimplantation genetic diagnosis: state of the art 2011.

For the last 20 years, preimplantation genetic diagnosis (PGD) has been mostly performed on cleavage stage embryos after the biopsy of 1-2 cells and PCR and FISH have been used for the diagnosis. The main indications have been single gene disorders and inherited chromosome abnormalities. Preimplantation genetic screening (PGS) for aneuploidy is a technique that has used PGD technology to examine chromosomes in embryos from couples undergoing IVF with the aim of helping select the chromosomally 'best' embryo for transfer.

Modification of the triplet repeat primed polymerase chain reaction method for detection of the CTG repeat expansion in myotonic dystrophy type 1: application in preimplantation genetic diagnosis.

Objective: To overcome problems associated with the use of triplet repeat primed polymerase chain reaction (TP-PCR) in preimplantation genetic diagnosis (PGD) of myotonic dystrophy type 1 (DM1).

Design: Clinical research study.

Setting: UCL Centre for PGD and Centre for Reproductive and Genetic Health.

Expression profiling of DNA repair genes in human oocytes and blastocysts using microarrays.

Background: The early preimplantation embryo relies on mRNA and protein from the oocyte to detect DNA damage and activate DNA repair, cell cycle arrest or apoptosis. Expression of some repair genes has been detected in mammalian oocytes and embryos; however, little is known about DNA repair gene expression in human blastocysts. In this study, DNA repair gene expression was investigated in human oocytes and blastocysts to identify the pathways involved at these stages and detect potential differences in repair mechanisms pre- and post-embryonic genome activation.

Preimplantation genetic diagnosis for myotonic dystrophy type 1 in the UK.

Myotonic dystrophy type 1 (DM1) is a dominant multisystemic disorder caused by expansion of a trinucleotide repeat in a non-coding region of DMPK. Prenatal diagnosis (PND) is available; however, the decision to terminate affected pregnancies is difficult as the extent of disability is hard to predict from the size of the expansion. In preimplantation genetic diagnosis (PGD) genetic analysis is carried out before the establishment of pregnancy.