Quick as Flash, resistant to impact and almost immune to the call of sleep: these are the "side effects" of some genetic variants, which give unexpected qualities.
The genes determine the color of our eyes and hair, height, skin tone, predisposition to certain diseases. But specific variations in the DNA sequence can give us powers from "superheroes", making us more resistant to some health problems, with surprising physical skills or more able to optimize the resources we draw every day. Here then are some particularly successful genetic mutations, and their consequences:
THE SPRINTER'S GENE
We all have the ACTN3 gene, but a variant of it is responsible for a greater ability to "sprint" the runners , because it encodes a protein - the alpha-actinin-3 - that controls the fast-twitch muscle fibers. A 2008 study showed that this allelic variant (alleles are the two or more alternative forms of the same gene), called R, is present in at least one copy in 95% of sprinters, and in two copies in 50% of them.
On the contrary, cross-country skiers (athletes specialized in endurance competitions) have the second allelic variant, called X, in higher percentage. This determines the absence of alpha-actinine-3, which contributes to the formation of "slow" muscles, more suited to sustaining a prolonged effort.
THOSE WHO NEVER SLEEP (OR ALMOST)
Imagine being able to feel completely recharged after 4 hours of sleep: this ability - cyclically claimed by politicians, entrepreneurs or scientists - has been associated with a series of genetic variants, in particular for the hDEC2 gene. The ability to regenerate with only a handful of hours a night would therefore seem to be a family gift, even if in the long run, too little sleep has very negative effects on health .
THE GIFT OF SUPERTASTERS
A quarter of the world population savors every bite with greater intensity: they are the supertasters , more inclined to sweeten the coffee and avoid very fatty foods. It appears that this ability is linked to a variant of the TAS2R38 gene, which encodes the bitter taste receptors. Another variant borne by the same gene is instead responsible for gustatory capacity below the average.
STEEL BONES
An extraordinarily dense skeleton with heavy, fracture-proof bones: a mutation in the LRP5 gene makes the bone virtually indestructible, as so Yale School of Medicine scientists have discovered by analyzing the genetic makeup of a family historically immune to bone problems. The same gene is also implicated in anomalies of the opposite type, which make the bones more fragile and favor osteoporosis.
THE GENIUSES OF CAFFEINOMANIACS
The genetic variants influence the way our body reacts to caffeine, and explain why the same dosage of coffee has different effects on each one. Two of these, close to the BDNF and SLC6A4 genes, influence the effects of coffee in the reward circuit - those that determine our desire to drink again.
Others determine the way in which the body metabolizes coffee: those who process it faster, probably will drink more, because its effects pass more quickly. Finally, others explain why some people fall asleep like little angels after a cup of espresso, while others have to stop their intake already after the early afternoon, if they do not want to spend a sleepless night.
MUTATIONS THAT PROTECT THE HEART
Cholesterol levels are very dependent on nutrition, but genetics also plays its part. Also some mutations in the gene that codes for the lipid transfer protein (CETP) can help to keep bad cholesterol (LDL) at bay: the deficiency of this protein promotes high levels of "good" HDL cholesterol, which helps to transfer cholesterol up to the liver, where it is eliminated. Therefore, people with this mutation are naturally protected from cardiovascular disease.