32.3: Personal Genomes

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In 2005, George Church initiated the Personal Genome Project [2]. Now that sequencing costs have rapidly decreased to the point that we can currently get the entire diploid human genome for $4000 (compare to $3 billion for a haploid human genome in the Human Genome Project), personal genome and sequence information is becoming increasingly affordable.

One important application for this information is in personalized medicine. Although many diseases are still complicated to predict, diagnose, and study, we currently already have a small list of diseases that are highly predictable from genome data. Examples include phenylketonuria (PKU), BRCA-mutation-related breast cancer, and hypertrophic cardiomyopathy (HCM). Many of these and similar diseases are uncertain (sudden onset without warning symptoms) and not normally checked for (due to their relative rareness). As such, they are particularly suitable as targets for personalized medicine by personal genomes, because genomic data provide accurate information that otherwise cannot be obtained. Already, there are over 2500 diseases (due to ~ 6000 genes) that are highly predictable and medically actionable, and companies such as 23andMe are exploring these opportunities.

As a final remark on the subject, Church remarked on some of his personal philosophy regarding personalized medicine. He finds many people reluctant to obtain their genomic information, and attributes this to a negative view among the general public toward GWAS and personalized medicine. He thinks that the media focuses too much on the failure of GWAS. The long-running argument against personalized medicine is that we should focus first on common diseases and variants before studying rare events. Church counterargues that in fact there is no such thing as a common disease. Phenomena such as high blood pressure or high cholesterol only count as symptoms; many ‘common diseases’ such as heart disease and cancer have many subtypes and finer categories. All along, lumping these diseases into one large category only has the benefit of teaching medical students and to sell pharmaceuticals (e.g., statins, which have fared well commercially but only benfit very few). Church argues that lumping implies a loss of statistical power, and is only useful if it is actually meaningful. Ultimately, everyone dies due to their own constellation of genes and diseases, so Church sees that splitting (personalized genomics) is the way to proceed.

Personal genomics provide information for planning and research. As a business model, it is analogous to an insurance policy, which provides risk management. As an additional benefit however, the information received allows for early detection, and consequences may even be avoidable. Access to genomic information allows one to make more informed decisions.