The turn of the century witnessed the sequencing of the first human genome. For the first time in history, mankind knows how to spell “human” in the language used by the nuclei of our cells – an alphabet composed of long chains of four DNA “letters” or molecules (called “bases”) – guanosine (G), adenosine (A), thymidine (T), and cytosine (C). It turns out that “human” (the human genome) is actually a long word (over 6 billion letters long) in this language called the genetic code. Learning the sequence for the first human took over a decade and billions of dollars. This achievement was considered to be as significant as the first moon landing. Now, just a decade and a half later, we can deduce the sequence of any one of us for a little over $1000 and in a week or so. The challenge for the rest of the century will be to better understand this information.
The genetic code is a subtle and intricate language in which each of us is spelled somewhat differently, but with broad similarities. Most of us are written as pairs of 23 “chapters” called chromosomes. These chromosomes have a total of about 30,000 “verses” called genes – each of which spell out a different protein building block. Too many or too few chromosomes results in problems like Down Syndrome. A missing, defective, or the wrong number of copies of, a gene can cause problems like Sickle Cell Anemia and possibly contribute to Autism. In addition to these genes, the chromosomes contain billions of bases which don’t code for genes. These “non-coding” sequences are probably “punctuation” for these genes (dictating when the cell reads each one and acts on the information). There’s a lot of supposed “junk” DNA that some people think just hitchhikes in our cells from generation to generation. We will probably learn that a lot of this “junk” DNA is not junk at all, but controls our being in ways we don’t yet understand.
My goal for this newsletter is to allow experts in fields related to the study of genomes (genomics), human or otherwise, to share their knowledge. Topics can be directly related to advances in genome sequencing or interpretation (bioinformatics), how these advances impact society, or (somewhat more broadly) how this and other advances in data handling can make medicine more personal or precise.
I look forward to your comments.
Geoffrey Routh, Ph.D.