DANIEL BUENOResearchers got a surprise when they finished sequencing all the human genetic material in 2000: human beings only have about 30,000 genes. This number is nearly the same as corn, which has approximately 20,000. In addition to the relatively small number, scientists were intrigued by another detail. They knew that genes made up the characteristics of each individual, but results showed that 45% of the DNA did not appear to have any function. That is why it was called Junk DNA, a name it carries today. As time passes, new studies show that Junk DNA is essential for regulating and controlling gene expression. In other words, it determines the stem cell differentiation in neurons, for example. If the Junk DNA expresses itself in the wrong way or at the wrong time, it can cause tumors to form. The issue was revisited in September with the publication of results from the Encode project, involving researchers from several countries who say they have determined how 80% of the Junk DNA work. Encode showed that this universe of 30,000 genes may be like a cake recipe in which taste and appearance may be completely different, depending on how the ingredients are added and mixed together. This vast combination of genes explains why people are so different from one another. Encode is now trying to determine which genetic compositions cause people to have, or prevents them from having, a particular disease.
Marie-Anne Van Sluys,
University of São Paulo (USP)
