10 | New Scientist | 30 November 2019
A COMPANY called Genomic
Prediction has confirmed that at
least one woman is pregnant with
embryos selected after analysing
hundreds of thousands of DNA
variants to assess their risk of
causing disease. It is the first time
this approach has been used to
screen IVF embryos, but some
people think its use is unjustified.
“Embryos have been chosen
to reduce disease risk using
pre-implantation genetic testing
for polygenic traits, and this
has resulted in pregnancy,”
Laurent Tellier, CEO of Genomic
Prediction, told New Scientist. He
didn’t say how many pregnancies
there were, or what traits or
conditions were screened for.
A few genetic mutations lead
to serious disorders, such as cystic
fibrosis or Tay-Sachs disease.
It is already possible to screen IVF
embryos to identify those that
won’t develop these conditions.
But many disorders are
polygenic – that is, caused by
variations in many different genes
that each have a small and less
clear-cut effect. Geneticists
attempt to work out the overall
impact of thousands of gene
variants by sequencing people’s
DNA and calculating so-called
polygenic risk scores, but there
are big questions about how
accurate or useful these are.
Genomic Prediction, which
is based in New Jersey, is the first
company to offer polygenic risk
scores for embryos rather than
adults, including an option to
screen out embryos deemed
likely to have a very low IQ.
Using these scores to screen
embryos is controversial.
“It is inappropriate to use
pre-implantation genetic
diagnosis to screen out polygenic
risk factors for things like
cardiovascular disease,” says
Frances Flinter at Guy’s and StThomas’ NHS Foundation Trust
in the UK. “I think it’s a misuse
of the technology.”
Such screening places undue
emphasis on genetics when it isn’t
the biggest factor, she says. For
instance, our risk of heart disease
is typically determined by our diet,
whether we smoke, how much
exercise we take and so on.
“It’s completely different from
using pre-implantation genetic
diagnosis to select out embryos at
high risk of a very serious disorder,
when we can predict with complete
accuracy whether or not those
embryos will be affected,” she says.But Stephen Hsu, one of the
founders of Genomic Prediction,
says polygenic scores reveal that
a few people – those who score
among the top 3 per cent – have
a much higher risk of, say, breast
cancer or heart disease. The firm’s
tests aim to identify such genomes.
“These results are very
new,” says Hsu. “A typical
pre-implantation genetic
diagnosis expert who focuses
on single-gene conditions mightnot be aware of how strong the
polygenic predictions can be.”
Genomic Prediction is offering
polygenic screening to assess the
risk of diseases and abnormally
low IQ. A separate study has
looked at whether polygenic
screening could be used to select
for desirable traits. Shai Carmi
at the Hebrew University of
Jerusalem and his colleagues
fed genetic data into a computer
model to estimate the maximum
potential effect of selecting IVF
embryos on the basis of polygenic
scores for high IQ or height.
They found that the approach
could only increase height by
3 centimetres at most, and IQ
by an average of only 3 points
(Cell, doi.org/dfvf). Carmi says it
may be possible to achieve bigger
gains when we know more about
genetic variants.
He says his results don’t apply
to Genomic Prediction’s polygenic
risk screening because selection
for quantitative traits such
as height is different from
screening out embryos at high
risk of disease. ❚ZE
PHYR
/SCIENCE
PHOT
O^ LIBRAR
YNews
“It is the first time this kind
of genetic diagnosis has
been used for embryos
rather than adults”PhysicsMystery of the mass
of the neutrino could
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the neutrino. The particle, which
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The new upper limit of the
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“Neutrinos are a billion times
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Christian Weinheimer at the
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Identifying this facet of the
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Weinheimer and his
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Tritium Neutrino experiment
made their measurements using
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They analysed the decay of
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emits an electron and a neutrino
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(arxiv. org/abs/1909.06048).
“We are extremely happy and
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“It’s very, very exciting,” says
Melissa Uchida at the University
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“We may finally be able to
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thousands of DNA variants
in embryos may give clues
to future healthHuman geneticsMichael Le PageGenomic selection begins
New method of analysing IVF embryos’ genes used for first time