Geoffrey Ginsburg in Nature:
More and more people are getting their DNA sequenced. But the use of genetic data to inform medical decisions is lagging. More than a decade since the Human Genome Project was declared complete, fewer than 60 genetic variants are deemed worthy for use in clinical care, most for severe conditions in very young children. These genetic variants can guide medical decisions (see ‘Genes that doctors use’). By some estimates, women with certain variants in the BRCA genes have about an 80% chance of developing breast cancer, leading some who carry the mutation to opt for preventive mastectomies. Screening for faulty genes involved in iron transport can alert affected individuals to a need to alter their diets to avoid developing haemochromatosis, a toxic build-up of iron that damages the liver, heart and other organs. Mutations in the EGFR gene can indicate whether lung cancer will respond to expensive drugs with fewer side effects than standard chemotherapy. But five years after EGFR tests were commercialized, only around 6% of appropriate US patients were being genotyped, partly because their physicians were unaware of the tests2. Clinical trials have been used to assess whether genomic information yields practical benefits. A study3 of nearly 2,000 patients with HIV showed that genetic screening for a variant called HLA-B*5701 could help to prevent toxic reactions to the AIDS drug abacavir — a fact that is now written into US treatment guidelines.
…Such 'pharmacogenomic' applications — in which genetic markers are used to fit drugs to patients — are among the most promising areas for collecting evidence during clinical care. In Thailand, about 12% of people have genetic predisposition to Stevens–Johnson syndrome, in which certain medications trigger a blistering, life-threatening rash. The government has sponsored a programme in which any Thai citizen can be genotyped to predict reactions to problematic drugs such as carbamazepine, commonly used to control seizures. Ramathibodi Hospital in Bangkok provides a health card for patients with risky genetic variants to present to pharmacists, alerting them to provide alternative medications. Whether decreased toxicity merits the use of less-effective drugs is being evaluated.
More here.
