the Oxford Scientist
O
ne hundred and fifty years ago, in a called a SNP chip to rapidly examine 700,000 laboratory in Germany, a young sci‐ SNPs and determine their identity. They can entist named Friedrich Miescher iden‐ then compare how similar your SNPs are to
tified an unusual new chemical while studying other people’s or look for SNPs associated with white blood cells. At first scientists assumed it diseases. This process makes genetic test kits both was unimportant, but then they began to un‐ useful and potentially misleading. cover its remarkable structure: a double helix
DNA firms tout the promise of helping
held together like a zip by pairs of chemical people understand their health. Most test kits building blocks, nucleotides known by their ini‐ look at many SNPs associated with disease - the tials A, C, T, and G. Even more impressive, the most famous probably being BRCA. Mutations sequence of these nucleotides blocks encodes in‐ in the BRCA gene can increase a woman’s risk of formation about proteins, the workhorse mo‐ breast cancer from 12.5 % to up to 90%. Check‐ lecules of cells. Today, home testing kits allow ing for disease-causing variations seems like a anyone to access their DNA sequence. But with good thing. Knowing their risk allows women science racing ahead of public understanding of to take proactive steps like Angelina Jolie, who genetics, we risk misunderstanding and misusing had a double mastectomy when her BRCA this information–with worrying consequences.
mutation was found. However, the reality is not
By one estimate, 1 in 25 Americans had used so simple. one by 2017. Only a few among them, however,
In a recent paper, scientists at the University
actually understood how they work. The basis of of Exeter found that more than 84% of SNP chip these tests is the single nucleotide polymorphism results showing a rare mutation in the BRCA (SNP). This is a location in the DNA where the gene were actually false positives, suggesting that specific nucleotide widely varies among the pop‐ 84% of the women told they have a rare BRCA ulation. DNA testing companies use a device variant are healthy. SNP chip results can lead to
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Tiffany Duneau
