Page 12 - aruba-today-20210108

A12 HEALTH
Friday 8 January 2021
Identical twins aren't perfect clones, research shows

lieved that physical differences be-
tween identical twins were related
mostly to environmental factors,
such as nutrition or lifestyle.
Jan Dumanski, a geneticist at Up-
psala University in Sweden, who
was not involved in the new paper,
praised it as "a clear and important
contribution" to medical research.
"The implication is that we have to
be very careful when we are using
twins as a model" for teasing apart
the influences of nature and nur-
ture, he said.
Previous studies, including a 2008
paper in The American Journal
of Human Genetics, have identi-
fied some genetic differences be-
tween identical twins.
The new study goes beyond earlier
work by including DNA of parents,
children and spouses of identical
twins. That allowed the research-
ers to pinpoint when genetic mu-
tations occurred in two different
kinds of cells — those present in just
one individual and those inherited
by that person's children. They also
found mutations that occurred be-
fore the developing embryo split
into two, setting the stage for twins.
In this Saturday, June 18, 2005 file photo, identical twins Alf, left, and Sven Fehnhanhn, left background, 79, from Kassel, Stefansson said that his team had
pose along with seven-month-old Luis Carl, right, und Albert Frank Millgramm, right background, during a twins' meeting
in Berlin. found pairs of twins where a mu-
Associated Press tation is present in all cells of the
body of one twin, but not found
By CHRISTINA LARSON tions that separate identical twins," ing DNA. in the other twin at all. However,
AP Science Writer said Kari Stefansson, a geneticist at On average, identical twins have "sometimes the second twin may
WASHINGTON (AP) — If you're an the University of Iceland and the 5.2 of these early genetic differ- show the mutation in some cells,
identical twin who's always resisted company deCODE genetics, and ences, the researchers found. But but not all cells," he said.
being called a clone of your sib- co-author of the paper published about 15% of identical twin pairs Nancy Segal, a psychologist who
ling, scientists say you have a point. Thursday in the journal Nature Ge- have more genetic differences, studies twins at California State
Identical twins are not exactly ge- netics. some of them up to 100, said Ste- University, Fullerton and was not
netically the same, new research A mutation means an alteration fansson. involved in the paper, called the
shows. in a sequence of DNA — a tiny These differences represent a tiny research "heroic and really signifi-
Scientists in Iceland sequenced change that is not inherently good portion of each twin's genetic cant."
DNA from 387 pairs of identical or bad, but can influence physical code, but they could influence "This will force scientists to refine
twins — those derived from a single features or susceptibility to certain why one twin is taller or why one our thinking about the influences
fertilized egg — as well as from their diseases. twin is at greater risk for certain of genetics and environment," she
parents, children and spouses. That They can occur when a cell divides cancers. said. "Twins are very alike, but it is
allowed them to find "early muta- and makes a slight error in replicat- Previously, many researchers be- not a perfect similarity."q

How quickly do I need a second COVID-19 vaccine shot?

a few weeks apart. ing out the Pfizer vaccine data to demonstrate that
People should get some and one by Astrazeneca protection after the first
degree of protection within that requires two doses giv- dose is sustained after 21
two weeks of the first shot, en four weeks apart. days," Pfizer said.
with the second shot bring- To get more first shots into U.S. regulators agreed, say-
ing about the vaccine's full people and give them at ing too few people in the
protection. For the vaccine least some degree of pro- Pfizer and Moderna vac-
by Pfizer and Germany's Bi- tection, the UK says it's OK cine studies missed their
oNTech, the second shot is to delay the boosters for as scheduled boosters to
supposed to be after three long as 12 weeks. But that have enough data to show
weeks. For Moderna, it's strategy has been nixed the strategy might work.
four weeks. in the U.S., where regula- The timing of the shots
But how closely those tors say there's no science doesn't have to be exact in
Associated Press Illustration/Peter Hamlin guidelines should be fol- backing the approach. the U.S., though; the Cen-
lowed has been a point of A major concern is that ters for Disease Control and
By The Associated Press shot? difference for the United it's unknown how long the Prevention says the second
How quickly do I need a The first COVID-19 vaccines States and the United King- partial protection from one shots can be given up to
second COVID-19 vaccine in the U.S. require two doses dom, which has been roll- dose can last. "There is no four days earlier or later. q