and more. There are hundreds of
healthy Dutch people going about
their daily lives, defying the faulty
genes within them.
A similar study by Prof David van
Heel and his team at Queen Mary
University of London came out in
March 2016, looking at the DNA
of more than 3,200 British Pakistanis
living in east London. It revealed
38 people carrying faulty or missing
versions of genes linked to serious
diseases. Yet the majority were
perfectly healthy. In the close-knit
Pakistani community, where there are
high levels of marriage between blood
relatives, there’s an increased chance
that people will inherit two dodgy
copies of a given gene. And although
there are definitely higher levels of
genetic diseases in this group, they
aren’t as high as might be expected.
Similarly, a 2015 study on the
genetically reclusive Icelandicpopulation revealed that nearly
8 per cent of the island’s inhabitants
carry two copies of ‘bad’ versions
of disease-causing genes, but many
of them are perfectly fine.
These findings aren’t just limited
to humans either. Researchers have
discovered dogs carrying a genetic
variation that protects them against
the doggy version of Duchenne
muscular dystrophy.Real superheroes
Then, in April 2016, came the big one.
“Thirteen anonymous genetic
superheroes walk among us,”
proclaimed the headlines, reporting
on an impressive analysis of more
than half a million people’s genetic
make-up. A team of US researchers
known as the Resilience Project
discovered that this lucky handful
carry mutations that should leave
them with serious illnesses, yet aresomehow perfectly healthy.
Led by Dr Rong Chen at the Icahn
School of Medicine at Mount Sinai,
New York, along with Dr Eric Schadt
and Prof Stephen Friend, the scientists
trawled global databases containing
information about people’s DNA
and whether they were affected by
any illnesses. The team focused on
mutations responsible for childhood
genetic diseases, known as highly
penetrant Mendelian diseases
(see overleaf ), where carrying two
copies of a faulty gene, or even just
one in some cases, is enough to cause
severe effects.
To start with, Chen spotted around
15,000 individuals who could be
heroes, carrying ‘bad’ mutations in
nearly 200 genes linked to more than
160 severe diseases. Further analysis
narrowed this down to 300 people,
finally ending up with strong evidence
for the existence of just 13 whoAbove: The tests
by the Dutch team
found some
surprising genetic
mutations among
the population.
Left: SERPIN A1 is
the gene that
provides instructions
for making a type
of protein (blue) that
blocks the activity
of certain enzymes
(green). When there
are faults with
SERPIN A1,
structures in
the body can
break down.
February 2017 73