The Gene of the Week.

Most readers probably learned it in school: we carry two copies of every gene in us. Mutations in these genes can cause disease. We call it a recessive mutation if such a variant has to be inherited from mother and father, i.e. both copies of the gene in the child must be affected for a disease to manifest. For a dominant variant, on the other hand, it is sufficient if either the mother or the father inherits such a copy, because a single copy of this variant triggers the disease. An example of a devastating mutation with dominant inheritance is Huntigton’s chorea. This degenerative disease, which is unfortunately fatal without exception, is passed on to the child from an affected parent with a 50% probability. It does not matter whether the variant was inherited from the mother or the father for the course of the disease, because on the so-called autosomes (these are all chromosomes except the sex chromosomes X and Y), both copies of the DNA segments are actually equivalent. But is that really always true? Not quite! And that is one of many reasons why the subject of epigenetics is currently so popular.… Read more