Clinical genetics
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Cancer initiation and progression is controlled by both genetic and epigenetic events. The complexity of carcinogenesis cannot be accounted for by genetic alterations alone but also involves epigenetic changes. Epigenetics refers to the study of mechanisms that alter gene expression without altering the primary DNA sequence. ⋯ Aberrant epigenetic modifications probably occur at a very early stage in neoplastic development, and they are widely described as essential players in cancer progression. Recent advances in epigenetics offer a better understanding of the underlying mechanism(s) of carcinogenesis and provide insight into the discovery of putative cancer biomarkers for early detection, disease monitoring, prognosis, and risk assessment. In this review, we summarize the current literature on epigenetic changes causing genetic alterations that are thought to contribute to cancer, and discuss the potential impact of epigenetics future research.
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The delivery of personalized genomic medicine (refer Table 1 for a comparison of genomic vs genetic medicine and box 1 for glossary) hinges on obtaining personal genomic data through genome-wide association studies (GWAS) or whole-genome sequencing. After the completion of the human genome project (see box 2 for human genome projects and its derivative projects) in 2003, there appeared to be a period of euphoric optimism that as soon as the cost of sequencing the whole human genome could be brought down to an affordable range, the promise of personalized medicine would become a reality. However, inasmuch as the miraculous technological advancements are making whole-genome data acquisition an inexpensive reality, we are also starting to appreciate that making sense of the enormous amount of genomic data is a far bigger hurdle. Issues, both scientific and ethico-legal, will have to be addressed as genomic data are been pushed for clinical and direct-to-consumer utilization. [Table: see text].
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The hippocampus is a primary region of the brain controlling the formation of memories and learned behaviours. The ability to learn or form a memory requires a neuron to translate a transient signal into gene expression changes that have a long-lasting effect on synapse activity and connectivity. ⋯ Animal models for many of these disorders are emerging and advancing our understanding of the molecular mechanisms linking epigenetic regulation and cognitive function. Here, we review how chromatin remodelling proteins implicated in MR/ID contribute to the development of the hippocampus and memory formation.
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Pre-implantation genetic diagnosis (PGD) is generally defined as the testing of pre-implantation stage embryos or oocytes for genetic defects. It has been developed for couples whose potential offspring are at risk of severe Mendelian disorders, structural chromosome abnormalities or mitochondrial disorders. Pre-implantation embryo diagnosis requires in vitro fertilization, embryo biopsy and either using fluorescent in situ hybridization or polymerase chain reaction at the single cell level. ⋯ However, diagnosis from a single cell remains a technically challenging procedure, and the risk of misdiagnosis cannot be eliminated. An ethical discussion of the question of whether PGD is acceptable at all-the 'desirability question'-is a rearguard action. Discussion must primarily focus on the conditions of exercising due caution in and the dynamics of PGD.
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Women with a BRCA1 or BRCA2 mutation are at an elevated risk of developing breast and ovarian cancer; however, it is unclear to what extent family history influences the uptake of cancer prevention options. Women with a BRCA1/2 mutation completed a follow-up questionnaire that assessed uptake of cancer preventive options. The pedigree of each woman was reviewed, and information was recorded on cancers diagnosed in relatives. ⋯ Having a mother or sister with ovarian cancer significantly predicted the uptake of prophylactic oophorectomy (OR = 1.6, p = 0.04). Women with a BRCA2 mutation were less likely to have a prophylactic oophorectomy than those with a BRCA1 mutation (OR = 0.49, p = 0.0004). Among women with a BRCA1 or BRCA2 mutation, family history predicts the uptake of prophylactic mastectomy and prophylactic oophorectomy.