Truly blessed are those who always stay skinny no matter what or how many times they eat — thanks to their genes. A new study says extra copies of certain genes in some people are much more likely to make them skinny.
Part of chromosome 16 – one of the 23 pairs of chromosomes – which contains 28 genes, is duplicated in one out of every 2,000 people, making men 23 times and women five times more likely to be underweight.
Duplications in this region have previously been linked with schizophrenia, and deletions with autism, reports the journal Nature.
Each person normally has a copy of each chromosome from each parent, so we have two copies of each gene. But sometimes parts of a chromosome can be duplicated or deleted, causing an abnormal ‘dosage’ of genes.
Researchers from Imperial College London and University of Lausanne, Switzerland, analyzing DNA of over 95,000 people, have identified that duplication of a part of chromosome 16 is associated with being underweight, defined as a a body mass index below 18.5.
Last year, the same researchers discovered that people with a missing copy of these genes are 43 times more likely to be morbidly obese.
Philippe Froguel who led the study, said: “The dogma is that we have two copies of each gene, but this isn’t really true.
“The genome is full of holes where genes are lost, and in other places we have extra copies of genes. In many cases, duplications and deletions have no effect, but occasionally they can lead to disease.”
“This is the first genetic cause of extreme thinness that has been identified… If a child is not eating, it’s not necessarily the parents’ fault,” added Froguel.