Preimplantation genetic testing (PGT) for monogenic disorders and assisted reproductive technology have evolved and progressed in tandem. PGT started with Bio Med Frontiers single-cell polymerase chain reaction (PCR) followed by fluorescent in situ hybridisation for a limited number of chromosomes, later called ‘preimplantation genetic diagnosis (PGD) version 1’.
This review highlights the various molecular genetic techniques that have evolved to detect specific inherited monogenic disorders in the preimplantation embryo.
Literature review in English was performed in PubMed from 1990 to 2021, using the term ‘preimplantation genetic diagnosis’. With whole-genome amplification, multiple copies of embryonic DNA were created. This helped in avoiding misdiagnosis caused by allele dropout.
Multiplex fluorescent PCR analysed informative short tandem repeats (STR) and detected mutations simultaneously on automated capillary electrophoresis sequencers by mini-sequencing.
Comparative genomic hybridisation (CGH) and array CGH were used for 24 chromosome aneuploidy screening.
Subsequently, aneuploidies were detected by next-generation sequencing using single-nucleotide polymorphism arrays, while STR markers were used for haplotyping. ‘PGD version 2’ included an accurate marker-based diagnosis of most monogenic disorders and detection of aneuploidy of all chromosomes.
Human leukocyte antigen matching of embryos has important implications in diagnosis and cure of haemoglobinopathies and immunodeficiencies in children by means of matched related haematopoietic stem cell transplantation from an unaffected ‘saviour sibling’ obtained by PGT.
Clinical utility of abdominal multidetector CT in 85 goats with suspected abdominal disease.
- Diagnosing the cause of abdominal disease in goats can be challenging. Clinical history, physical investigation, and Our supplier laboratory findings do not always allow definitive identification of an intra-abdominal disease or the underlying cause.
- Multidetector CT (MDCT) has become more readily available and now often replaces or augments other abdominal imaging techniques.
- The objective of this retrospective, observational, descriptive study was to investigate the clinical utility of MDCT for evaluation of the abdomen in goats with suspected abdominal disease involving the urinary, gastrointestinal, reproductive tracts and abdominal wall. Medical records (1/2009-12/2017) were reviewed for all goats undergoing an abdominal MDCT.
- Signalment, clinical history, examination and MDCT findings and outcome were recorded and categorized by abdominal organ system and wall lesion.
- Clinical problems and MDCT findings were compared in the various abdominal categories. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic odds ratio (OR) were calculated for MDCT, using clinical examination findings as the reference standard.
- A total of 85 goats underwent an abdominal MDCT examination. The sensitivity of MDCT for detecting urinary, gastrointestinal, reproductive tract, and abdominal wall abnormalities in goats with clinical problems related to these body systems was high at 94.7 %, 78.3%, 94.1%, and 100%, and the specificity was high at 95.6%, 96.7%, 93.9%, and 100%, respectively. The PPV was 94.7%, 90.0 %, 80.0%, and 100.0%, the NPV was 95.6%, 92.1%, 98.4%, and 100%, and the OR were 387.0, 104.4, 248.0, and infinite. In conclusion, findings supported the use of MDCT as an adjunct diagnostic test for assessing goats with abdominal disease.
- Challenges facing Indigenous transplant patients living in Canada: exploring equity and utility in organ transplantation decision-making.
Indigenous peoples in Canada and in the Circumpolar North face a higher disease burden leading to end-stage organ failure and face geographic and systemic barriers to accessing health-care services, including those for end-stage organ failure and organ donation and transplantation (ODT).
To address these issues, I present a think tank model used in Saskatchewan, Canada, which focused on ODT and recommended research and policy changes that address inequitable Indigenous access to ODT, most specifically in northern and remote regions.
Over the past three years, think tank members, comprised of Indigenous cultural leaders, elders, and persons with lived experience in ODT, and complemented by medical and advocacy exports, have highlighted equity and utility issues as key concerns, and discussed ways in which these issues can be addressed. Recommendations include culturally-safe methods for documenting and tracking Indigenous identity, development of training to address culturally specific needs, and additional funding to support Indigenous transplant donors and recipients.
Exercise in preventing falls for men with prostate cancer: a modelled cost-utility analysis.
Men who receive androgen deprivation therapy (ADT) for prostate cancer (PCa) are a vulnerable falls population due to the side effects of treatment.
The purpose of this paper is to determine the cost-effectiveness of exercise in preventing falls and fractures for this high-risk population in Australia.
A decision analytic model was constructed to evaluate the cost-utility of an exercise intervention compared to usual care from a health system perspective. The intervention comprised two 1-h sessions of supervised exercise per week over 1 year for men with non-metastatic PCa receiving curative radiation therapy and ADT.
A Markov model simulated the transition between five health states:
(1) at risk of falling;
(2) at recurrent risk of falling;
(3) fracture (minor or major);
(4) non-fracture injury (minor or major); and
(5) death. Model inputs including transition probabilities and utility scores were obtained from published meta-analyses, and costs were drawn from Australian data sources (e.g. Medical Benefits Schedule).
The model time horizon was 3 years, and costs and effects were discounted at 5% annual rate. Costs and quality-adjusted life years (QALYs) were aggregated and compared between the intervention and control to calculate incremental net monetary benefit (iNMB).
Uncertainty in the results was explored using deterministic and probabilistic sensitivity analyses (PSA).
At a willingness-to-pay of AU$50,000 per QALY, the exercise intervention dominated, as it was less costly and more effective than usual care. The iNMB was $3010 per patient. The PSA showed a 58% probability the intervention was cost-effective.
Conclusion: This is the first modelled economic evaluation of exercise for men with PCa. Our results suggest supervised exercise is cost-effective in reducing the risks of falls and fractures in this population.
Development, validation, and utility of species-specific diagnostic markers for detection of Peronospora belbahrii.
Peronospora belbahrii is an oomycete and cause of basil downy mildew, one of the most destructive diseases affecting basil production worldwide.
Disease management is challenging due to wind-dispersed sporangia and contaminated seed, therefore, identifying P. belbahrii in seed-lots before sale or planting, or in the field before symptoms develop could allow for timely deployment of disease management strategies.
In this study, a draft genome assembly and next generation sequencing reads for P. belbahrii, and publicly available DNAseq and RNAseq reads of several other downy mildew pathogens, were incorporated into a bioinformatics pipeline to predict P. belbahrii-specific diagnostic markers.
The specificity of each candidate marker was validated against a diverse DNA collection of P. belbahrii, host tissue, and related oomycetes using PCR. Two species-specific markers were identified and used to develop a highly sensitive probe-based real-time qPCR assay that could detect P. belbahrii in leaf tissue and seed samples.
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Both markers were capable of reliably detecting as low as 500 fg/µl of P. belbahrii genomic DNA and as few as 10 sporangia. The qPCR assay was then validated with seed samples collected from a basil cultivar experiment. In total, 48 seed samples were collected and tested; P. belbahrii was detected in samples of all cultivars at estimated concentrations of 600 fg/µl up to 250 pg/µl and at as few as 10 sporangia up to >1,000 sporangia. The markers and assays are valuable for diagnostics and for identifying P. belbahri-contaminated seed-lots, to mitigate the effects of future basil downy mildew epidemics.