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Biomedical subjects

Joe Leigh Simpson

Publications and source records attributed to Joe Leigh Simpson.

At least 19 recordsLinked to original sources
PubMed2006

Growth differentiating factor-9 mutations may be associated with premature ovarian failure.

OBJECTIVE: To determine whether perturbations of the growth differentiating factor-9 (GDF9) gene are associated with premature ovarian failure (POF). DESIGN: Mutational analysis of the GDF9 gene in 61 women with POF. SETTING: Academic institution. PATIENT(S): Sixty-one women with POF; 60 control women. INTERVENTION(S): Peripheral blood sampling, genomic DNA extraction, mutational screening, and DNA sequencing. MAIN OUTCOME MEASURE(S): Genetic perturbations in GDF9 that are associated with POF. RESULT(S): A single missense mutation, substitution of a cytosine residue with thymidine in exon 1 of GDF9, was found in a white woman in whom POF developed at age 22. This mutation occurred in a highly conserved proprotein region and resulted in replacement of a nonpolar amino acid (proline) with a polar amino acid (serine) at position 103. Neither 60 control women nor 60 other women with POF demonstrated this genetic perturbation. Exon 2 showed only previously recognized single nucleotide polymorphisms. CONCLUSION(S): GDF9 mutations may be one explanation for POF, albeit uncommon.

Adult↗
PubMed2006

The FMR1 premutation and reproduction.

OBJECTIVE: To update clinicians on the reproductive implications of premutations in FMR1 (fragile X mental retardation 1). Fragile X syndrome, a cause of mental retardation and autism, is due to a full mutation (>200 CGG repeats). Initially, individuals who carried the premutation (defined as more than 55 but less than 200 CGG repeats) were not considered at risk for any clinical disorders. It is now recognized that this was incorrect, specifically with respect to female reproduction. DESIGN AND SETTING: Literature review and consensus building at two multidisciplinary scientific workshops. CONCLUSION(S): Convincing evidence now relates the FMR1 premutation to altered ovarian function and loss of fertility. An FMR1 mRNA gain-of-function toxicity may underlie this altered ovarian function. There are major gaps in knowledge regarding the natural history of the altered ovarian function in women who carry the FMR1 premutation, making counseling about reproductive plans a challenge. Women with premature ovarian failure are at increased risk of having an FMR1 premutation and should be informed of the availability of fragile X testing. Specialists in reproductive medicine can provide a supportive environment in which to explain the implications of FMR1 premutation testing, facilitate access to testing, and make appropriate referral to genetic counselors.

Adolescent↗
PubMed2006

Professional self-regulation for preimplantation genetic diagnosis: experience of the American Society for Reproductive Medicine and other professional societies.

Professional societies that are stakeholders in preimplantation genetic diagnosis have democratically elected officers and favor self-regulation. Their practice guidelines are cognizant of societal needs and allow for introduction of new technologies. These societies have demonstrated the ability for professional self-regulation by collection, validation, and promulgation of center-specific results.

Fertilization in Vitro↗
PubMed2006

Recovery and amplification of placental RNA from dried maternal blood spots: utility for non-invasive prenatal diagnosis.

Methods utilizing circulating cell-free RNA in plasma have clinical applications for cancer and prenatal genetic analysis. Given these potential roles, the feasibility of detecting placental specific RNA in dried maternal blood spots after storage at room temperature for varying lengths of time was investigated. Using real-time polymerase chain reaction (PCR), positive amplification of placental-specific beta-human chorionic gonadotrophin transcripts was demonstrated in nine of 11 dried blood samples from first and second trimester pregnancies stored at room temperature for up to 4 weeks. This work demonstrates feasibility in isolation and amplification of placental mRNA using dried maternal blood spots. With the development of fetal and placental RNA markers, this approach would allow simplified collection, transport, and storage of samples for prenatal genetic diagnosis and pregnancy related complications.

Chorionic Gonadotropin, beta Subunit, Human↗
PubMed2006

Endocervical fetal trophoblast for prenatal genetic diagnosis.

PURPOSE OF REVIEW: For over a decade, methods of first-trimester, noninvasive prenatal genetic diagnosis have been actively pursued by many investigators. Isolation of fetal trophoblast from endocervical specimens remains an attractive approach, given the greater numbers of fetal cells than in maternal blood and the better potential for fetal-cell identification based on markers specific for a single cell type (trophoblasts). RECENT FINDINGS: Current studies demonstrate feasibility in identification and molecular analysis of fetal trophoblast cells for prenatal genetic testing. Sampling methods involving lavage, cytobrush, or aspiration of cervical specimens, however, have limitations in the recovery of trophoblasts. SUMMARY: Clinical applications await further systematic studies to determine safety and accuracy in recovery.

Cervix Uteri↗
PubMed2006

Quantity versus quality: optimal methods for cell-free DNA isolation from plasma of pregnant women.

PURPOSE: Methods to isolate cell-free fetal DNA from maternal plasma are critical in developing noninvasive fetal DNA testing strategies. Given that plasma consists of heterogeneous DNA-size fragments in a complex mix of proteins, recovery and analysis of this DNA are understandably inefficient. To facilitate recovery, we performed qualitative and quantitative analysis of DNA isolated from maternal plasma. METHODS: DNA isolated from maternal blood (n = 15) was compared using five different DNA isolation protocols: two conventional, two column-based, and one magnetic-bead based. Purity and concentration of DNA recovered were determined with a NanoDrop spectrophotometer. Real-time polymerase chain reaction quantification of the beta-globin and DYS1 loci was performed to determine total and fetal-specific genome equivalents, respectively. RESULTS: DNA quality and quantity were different among the five methods tested. Although purity and concentration of total DNA were greatest with the conventional boiling-lysis approach, correct detection of a male fetus was achieved in only 62.5% of cases. DNA isolation using the magnetic beads yielded the highest quantity of total DNA (2018.83 +/- 4.09 GEq/mL), with 100% fetal DNA detection. CONCLUSIONS: Optimal plasma DNA recovery protocols must take into account DNA purity and concentration. We confirm that the magnetic-beads method provides a fast, simple, sensitive, and specific approach to purify plasma DNA. The resulting high-quality DNA facilitates efficient examination of fetal DNA sequences.

DNA↗
PubMed2006

Hypoxia-induced membrane-bound apoptotic DNA particles: potential mechanism of fetal DNA in maternal plasma.

Fetal DNA is found in the plasma of pregnant women that appears to be stable for PCR amplification. Although the underlying mechanism giving rise to this DNA in plasma remains unclear, the source of these fragments may be from apoptotic bodies (Apo-Bodies) created from dying cells. Trophoblast apoptosis is essential for normal placental development, given the enormous amount of proliferation, differentiation, and migration during pregnancy. Through flow cytometric analysis coupled with real-time PCR, our lab has shown that aggregates of acridine orange (AO)-stained material (apoptotic particles) are resistant to DNase treatment, disrupted by sodium dodecyl sulfate (SDS), and contain fetal DNA. Because the placenta continuously re-models in an hypoxic environment, our hypothesis is that fetal DNA in maternal plasma comes from hypoxia-induced dying trophoblasts and that this DNA circulates predominantly in the form of Apo-Bodies. We have developed a model culture system for analysis of Apo-Bodies derived from JEG-3 cells, an extravillous trophoblastic cell line, undergoing various methods of cell death: hypoxia-induced, etoposide-induced, and heat stress (necrosis like)-induced cell death. Under conditions of similar propidium iodide (PI) uptake, suggesting comparable levels of death, both hypoxia- and etoposide-induced Apo-Bodies increase in concentration over time, whereas heat-induced levels of particles remain fairly constant, indicating that production of DNA-associated Apo-Bodies is a continuous process. Hypoxia, which is likely to be responsible for trophoblast cell death in vivo, produced membrane-bound Apo-Bodies containing DNA. Our results are consistent with the characteristics of membrane-bound particles containing fetal DNA found in maternal plasma.

Apoptosis↗
PubMed2005

Research agenda for preterm birth: recommendations from the March of Dimes.

Preterm birth (PTB) is a common, serious, and costly health problem affecting nearly 1 in 8 births in the United States. Burdens from PTB are especially severe for the very preterm infant (<32 weeks' gestation), comprising 2% of all US births. Successful prevention needs to include newly focused and adequately funded research, incorporating new technologies and recognition that genetic, environmental, social, and behavioral factors interact in complex pathogeneses and multiple pathways leading to PTB. The March of Dimes Scientific Advisory Committee created this prioritized research agenda, which is aimed at garnering serious attention and expanding resources to make major inroads into the prevention of PTB, targeting six major, overlapping categories: epidemiology, genetics, disparities, inflammation, biologic stress, and clinical trials. Analogous to other common, complex disorders, progress in prevention will require incorporating multipronged risk reduction strategies that are based on sound scientific discovery, as well as on effective translation into clinical care.

Charities↗
PubMed2005

Preimplantation genetic diagnosis reduces pregnancy loss in women aged 35 years and older with a history of recurrent miscarriages.

OBJECTIVE: To determine whether preimplantation genetic diagnosis (PGD) and transfer of euploid embryos would decrease spontaneous abortion rates in recurrent miscarriage (RM) patients. DESIGN: Controlled clinical study. SETTING: In vitro fertilization centers and PGD reference laboratory. PATIENT(S): Recurrent-miscarriage patients with three or more prior lost pregnancies with no known etiology. INTERVENTION(S): Biopsy of a single blastomere from each day 3 embryo, followed by fluorescence in situ hybridization analysis. MAIN OUTCOME MEASURE(S): The rate of spontaneous abortions in RM subjects undergoing PGD were compared with [1] their own a priori expectations and [2] a comparison group of women undergoing PGD for advanced maternal age (> or =35 years). RESULT(S): Before PGD, RM patients had lost 87% (262/301) of their pregnancies, with an expected loss rate of 36.5%. After, they only lost 16.7% pregnancies. This difference was mostly due to reduction in pregnancy loss in the > or =35-years age subgroup, to 12% from an expected 44.5%. CONCLUSION(S): Preimplantation genetic diagnosis aneuploidy screening has a beneficial effect on pregnancy outcome in RM couples, especially those in which the woman is aged > or =35 years. Our data indicate that PGD reduces the risk of miscarriage in RM patients to baseline levels.

Abortion, Habitual↗
PubMed2005

Quantitative DNA perturbations of p53 in endometriosis: analysis of American and Icelandic cases.

OBJECTIVE: To investigate quantitative aberrations involving p53 copy numbers in eutopic endometrial and endometriotic tissue from two populations. DESIGN: Comparative analysis of normal and diseased tissue. SETTING: Tissue specimens collected in Iceland and USA. PATIENT(S): Subjects with moderate/severe endometriosis (Iceland, n = 26; USA, n = 45). Paraffin-embedded tissue from 19 matched Icelandic cases and seven unaffected controls. American cases were fresh surgical tissue from 17 matched cases and 28 unaffected controls. DNA isolation and real-time polymerase chain reaction (PCR) with TaqMan assay were performed. MAIN OUTCOME MEASURE(S): The frequency of p53 loss and/or gain based on quantitative differences for copy numbers of p53 located on chromosome (17p) and GAPDH on a control locus (chromosome 12p). RESULT(S): Among American cases, significant p53 gain (n = 13) or loss (n = 4) was observed in 17 of 21 cases. In Icelandic cases this was not seen to the same degree. Mean normalized p53 values were 3.46 and 1.16 copies per reaction, respectively. Significant differences were observed between normalized p53 in the control blood and affected tissue for the American and Icelandic cases compared to standard GAPDH control but not in normal Icelandic and American endometrium. CONCLUSION(S): The results continue to support a role for nonrandom somatic p53 locus alterations in the pathogenesis of late or severe-stage endometriosis. Differences between Icelandic and American subjects have implications for generalization of genome-wide approaches.

DNA↗
PubMed2005

Genetic testing of embryos: a critical need for data.

Preimplantation genetic diagnosis (PGD), the genetic testing of embryos developed through IVF is one of the fastest growing techniques in reproductive medicine and IVF. Some suggest that PGD will become part of every IVF cycle in the future. The growing popularity of PGD has highlighted the fact that there are no comprehensive data available about the use of PGD, its accuracy, or the health outcomes of babies born following PGD. For patients, practitioners, and policymakers alike, such information is critical. To address the gaps in knowledge, a working group of the leading experts in the development and practice of PGD and IVF has begun to design a database to collect information about PGD as practised in the United States.

Databases, Factual↗
PubMed2005

Preimplantation genetic diagnosis (PGD) for heritable neoplasia.

UNLABELLED: Especially applicable for heritable neoplasia, preimplantation genetic diagnosis (PGD) is possible for any Mendelian disorder whose gene has been localized, whether the molecular basis is known or not. METHODS AND RESULTS: PGD requires DNA from gametes (oocytes) or embryos before 6 days postconception, when implantation occurs. Approaches include 1) polar body biopsy, 2) blastomere biopsy (aspiration of one or two cells from the six- to eight-cell embryos at 2 or 3 days), and 3) trophectoderm biopsy, which allows recovery of 20 or more cells (20-50) from 125- to 150-cell, 5- to 6-day blastocysts. Of some 6000 PGD cycles worldwide, approximately 1500 have been performed for Mendelian indications. The approximately 25% live birth rates following PGD parallel the general U.S. experience for assisted reproductive technology. PGD has been accomplished for both cancer-specific disorders like adenomatous polyposis coli (APC), BRCA1, retinoblastoma, Li-Fraumeni syndrome, and von Hippel-Lindau syndrome (VHL), as well as disorders predisposing to neoplasia (Fanconi anemia, Wiskott-Aldrich syndrome). PGD also makes possible the identification and, hence, transfer of embryos of specific HLA genotypes. This allows cord blood harvesting for stem cell implantation into a moribund child, often an older sibling of the fetus. CONCLUSIONS: PGD is a complex, but achievable, approach especially applicable to Mendelian forms of neoplasia. PGD is an attractive addition to the prenatal diagnostic armamentarium, especially relevant to heritable neoplasia. PGD also makes possible novel indications having special relevance to heritable neoplasia.

Adult↗
PubMed2005

Elevated pregnancy losses at high and low extremes of maternal glucose in early normal and diabetic pregnancy: evidence for a protective adaptation in diabetes.

OBJECTIVE: Early pregnancy losses increase with marked hyperglycemia in diabetic pregnancy. However, mean loss rates do not differ from those of nondiabetic pregnancy. This observation might be explained by increased fetal losses at the extremes of glycemia in diabetic and nondiabetic pregnancy. To test this hypothesis, we examined relationships of proximate measures of prior glycemia, glycated protein and fructosamine, to pregnancy loss. RESEARCH DESIGN AND METHODS: A total of 389 diabetic and 429 nondiabetic pregnant subjects participated in the Diabetes In Early Pregnancy study. Glycated protein and fructosamine measurements were standardized as multiples of control values for each center (Z score). The logarithm of odds of pregnancy loss were plotted against Z scores and tested by logistic models. RESULTS: Mean pregnancy loss rates were 12% in diabetic and 13% in normal pregnancies. However, over six intervals of glycated protein in diabetic pregnancy, fetal loss rates at the upper and lower extremes (24 and 33%, respectively) were approximately threefold higher than the four intervening rates (8-14%). The odds ratio of pregnancy loss for these extreme intervals to the intervening intervals is 3.0 (P = 0.01). Nondiabetic losses showed a similar pattern. In confirmation, logit pregnancy losses were increased in a J-shaped curve at the glycemic extremes in normal (P < 0.019) and diabetic (P < 0.015) pregnancy. The upper glycemic extreme in diabetic pregnancy was two- to fivefold higher than in control pregnancy. CONCLUSIONS: Pregnancy losses are increased at the extremes of glycemia in both normal and diabetic pregnancy but at higher levels in diabetic pregnancy. The data suggest defensive adaptations against hyperglycemia in diabetic pregnancy.

Abortion, Spontaneous↗
PubMed2004

Cell-free fetal DNA in maternal blood: kinetics, source and structure.

The kinetics and structure of cell-free fetal DNA in maternal plasma is currently under investigation. Plasma fetal DNA seems quite stable albeit cleared rapidly following birth, suggesting continuous fetal DNA release into the maternal circulation during pregnancy. However, to understand better the kinetics of circulating DNA, studies to determine the biological (structural) form in which fetal and maternal DNA exist and the mechanisms underlying variation in plasma are warranted to ensure quantitative diagnostic reliability. It is likely that circulating fetal DNA is released from fetal and/or placental cells undergoing apoptosis. Thus, the majority of fetal DNA is proposed to circulate in membrane-bound vesicles (apoptotic bodies). This review summarizes the latest reports in this field.

Aneuploidy↗
PubMed2004

Nuclear chromosomal localization in human preimplantation embryos: correlation with aneuploidy and embryo morphology.

BACKGROUND: Spatial organization of chromosomes is hypothesized to reflect transcriptional activity and regulatory protein function. Preimplantation genetic diagnosis allows assessment of the spatial relationship of chromosomes in human blastomeres. We thus examined the localization of chromosomes 13, 16, 18, 21, 22, X and Y in blastomeres from 6-8-cell stage embryos, correlating localization to aneuploidy and embryo morphology. METHODS: Following fluorescence in situ hybridization to enumerate chromosomes 13, 16, 18, 21, 22, X and Y, signal positions were localized within one of four concentric shells. Statistical analysis compared chromosome localization between euploid and aneuploid blastomeres as well as morphologically normal and abnormal embryos. RESULTS: Of 98 embryos, 109 blastomeres were evaluated. Within chromosomally normal blastomeres, no difference in the location of all seven chromosomes (P</=0.10) was observed. However, a significant difference was observed between the organization of chromosomes in euploid versus aneuploid blastomeres (P</=0.001). Localization of chromosomes 13, 18, 21 and 22 was significantly different when an abnormality involving that chromosome existed (P</=0.001, P</=0.01, P</=0.025 and P</=0.01 respectively). CONCLUSIONS: We report for the first time that localization of chromosomes is altered in chromosomally aneuploid but not in chromosomally normal nor morphologically abnormal euploid blastomeres.

Adult↗