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Birth defects in children conceived by ICSI compared with children conceived by other IVF-methods; a meta-analysis.

BACKGROUND: Intracytoplasmic sperm injection (ICSI) is a method of assisted reproductive technology that involves the selection of a single sperm cell and the manual injection of this cell into the egg. The lack of relevant experimental studies, the nature of the technology involving non-natural selection of the fertilizing sperm, and possible damage to the egg have caused concern that ICSI could increase the risk of birth defects. Data from available cohort studies comparing ICSI with standard in vitro fertilization (IVF) should be combined to evaluate the risks involved with ICSI. METHODS: We reviewed more than 2500 titles and abstracts containing keywords related to ICSI and identified 22 scientific articles with data on birth defects among ICSI-births. A total of four peer-reviewed, non-overlapping prospective cohort studies provided reliable and comparable data on birth defects both for children conceived by ICSI and children conceived by standard IVF. These studies included a total of 5395 children born after ICSI. RESULTS: The pooled estimate of the risk of a major birth defect was a 1.12-fold increase after ICSI when compared with standard IVF (risk ratio = 1.12, 95% confidence interval (CI): 0.97-1.28, P = 0.12). There was no marked heterogeneity of risk ratios between these studies (P = 0.10). We found no significantly increased risks after ICSI for any of the categories cardiovascular defects, musculoskeletal defects, hypospadias, neural tube defects, or oral clefts. CONCLUSIONS: Our analysis does not indicate that the ICSI-procedure represents significant additional risks of major birth defects in addition to the risk involved in standard IVF. The data was limited, particularly on risks of specific categories of defects.

Cardiovascular Abnormalities↗

Differential regulation of imprinting in the murine embryo and placenta by the Dlk1-Dio3 imprinting control region.

Genomic imprinting is an epigenetic mechanism controlling parental-origin-specific gene expression. Perturbing the parental origin of the distal portion of mouse chromosome 12 causes alterations in the dosage of imprinted genes resulting in embryonic lethality and developmental abnormalities of both embryo and placenta. A 1 Mb imprinted domain identified on distal chromosome 12 contains three paternally expressed protein-coding genes and multiple non-coding RNA genes, including snoRNAs and microRNAs, expressed from the maternally inherited chromosome. An intergenic, parental-origin-specific differentially methylated region, the IG-DMR, which is unmethylated on the maternally inherited chromosome, is necessary for the repression of the paternally expressed protein-coding genes and for activation of the maternally expressed non-coding RNAs: its absence causes the maternal chromosome to behave like the paternally inherited one. Here, we characterise the developmental consequences of this epigenotype switch and compare these with phenotypes associated with paternal uniparental disomy of mouse chromosome 12. The results show that the embryonic defects described for uniparental disomy embryos can be attributed to this one cluster of imprinted genes on distal chromosome 12 and that these defects alone, and not the mutant placenta, can cause prenatal lethality. In the placenta, the absence of the IG-DMR has no phenotypic consequence. Loss of repression of the protein-coding genes occurs but the non-coding RNAs are not repressed on the maternally inherited chromosome. This indicates that the mechanism of action of the IG-DMR is different in the embryo and the placenta and suggests that the epigenetic control of imprinting differs in these two lineages.

Animals↗

Morphological features and measurements in a human fetus with karyotype 69, XXX: comparison with fetuses of the same CRL, without chromosomal anomalies.

A triploid fetus (karyotype 69, XXX) with crown-rump length (CRL) 94 mm, presenting micro- and retrognathia, low-set ears and crooked feet, was cleared and double-stained with alizarin red S and alcian blue for detecting the ossification patterns in the vertebral column, ribs, ischium, limbs, and face. Longitudinal measurements of some long bones in the upper (humerus, ulna, radius) and lower (femur, tibia, fibula) limb were taken. The values of both the total length (TL) and the ossified part (OL) of each long bone, as well as the OL/TL per cent ratio were considered. Reference points were located on the mandible, i.e. condylar process (Pcl), coronoid process (Pco), gnathion (GN), gonion (GO), superior symphyseal point (SSP) for measuring linear dimensions. Since the aim of this work was to assess the influence of triploidy 69, XXX the skeletal development and growth patterns, all values obtained in the examined specimen were related with those relative to a group of fetuses, without any detectable malformation and chromosomal anomalies, with a CRL mean value of 93 mm. Results evidenced that the triploid fetus presented growth restriction and that the vertebral centra ossification and the mandibular development were much delayed with the normal ossification patterns.

Alcian Blue↗