Clinical genetics
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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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Malignant hyperthermia (MH) is an autosomal dominant pharmacogenetic disorder of skeletal muscle characterized by disturbance of intracellular calcium homeostasis in the sarcoplasmic reticulum. Mutations of the ryanodine receptor 1 (RYR1) gene account for most cases, with some studies claiming up to 86% of mutations in this locus. However, RYR1 gene is large and variants are common even in the normal population. ⋯ Unexpectedly, four changes were also found in the same family and two in another. Our study confirms that MH is genetically heterogeneous and that a consistent number of cases are not due to RYR1 mutations. The discordance between in vitro contracture test status and the presence of a proven causative RYR1 mutation suggests that the penetrance may vary due to as yet unknown factors.