With some 20,000 genes in the human genome it’s difficult to imagine how a few missing copies might be a problem. However, if only a handful is lost, the impact on the individual is significant. Take for example the case of a genetic disorder known as Williams Syndrome. Carter (pictured) is four years old. Like hundreds of thousands worldwide, he is missing a tiny chunk from chromosome seven. The absence of only 25 genes seems to affect people in a very similar way. Individuals with Williams Syndrome experience developmental delay and are prone to heart defects. One of the missing genes, ELN encodes for the protein elastin. This stretchy protein helps to keep blood vessels supple. How the loss of other genes is linked to the characteristic social inhibition, musical propensity or very empathetic personalities of people with Williams Syndrome, has yet to be explained.
Written by Brona McVittie
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