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(2) PREDICTIVE
GENETIC TESTS RANGE FROM HIGHLY
USEFUL TO POTENTIALLY
HARMFUL
(3) WOULD
KNOWING YOUR GENETIC RISK CHANGE
YOUR BEHAVIOUR?
(4) GENES
AND ENVIRONMENT IMPORTANT IN
FAMILIES WITH
HISTORY OF HIGH CHOLESTEROL
(5) PRIMARY
CARE PRACTITIONERS NEED TO BECOME
GENETICALLY
LITERATE
(Value of family history in identifying
women at risk of venous
thromboembolism during oral contraception:
observational study)
http://bmj.com/cgi/content/full/322/7293/1024
Family history of venous thromboembolism
(blood clotting) is an
unsatisfactory predictor for identifying
common thrombophilic
defects in women without thrombosis before
taking oral
contraceptives, finds a study in this
week's BMJ.
A total of 324 women (mean age 34 years)
with no personal
history of venous thromboembolism were
screened for common
inherited thrombophilic defects before
taking oral contraceptives.
Before screening, the women were surveyed
to evaluate both
personal and family history of venous
thromboembolism. A
family history was considered positive
if a thromboembolism was
reported in any first or second degree
relatives.
The proportion of women with thrombophilia
was similar among
those with a positive history and those
with a negative history of
venous thromboembolism when both first
and second degree
family history was considered.
These findings suggest that family history
of venous
thromboembolism is an unsatisfactory predictor
for identifying
carriers of common thrombophilic defects
before taking oral
contraceptives. A policy of selective
screening may therefore
miss a substantial number of women at
increased risk of
thromboembolism when taking oral contraceptives,
conclude the
authors.
Contact:
Benilde Cosmi, Lecturer, Cardiovascular
Department, Division
of Angiology, S. Orsola-Malpighi University
Hospital, Bologna,
Italy
Email: bcosmi@med.unibo.it
(2) PREDICTIVE
GENETIC TESTS RANGE FROM HIGHLY
USEFUL TO POTENTIALLY HARMFUL
(The complexities of predictive genetic
testing)
http://bmj.com/cgi/content/full/322/7293/1052
Predictive genetic testing has the potential
to save lives through
targeted surveillance and preventive measures,
but a paper in this
week's BMJ reports that most genetic tests
carry a degree of
uncertainty, which limits their usefulness
and, in some cases, can
even be harmful to patients.
For some diseases, predictive genetic testing
is highly useful. For
example, testing for multiple endocrine
neoplasma type 2 - a rare
disorder leading to thyroid cancer - makes
it possible to identify
those who will benefit from preventive
surgery. For other
conditions, such as breast and ovarian
cancer, genetic testing can
be useful to identify those at increased
risk, but utility is limited
because of considerable uncertainty about
the predictive value of
the test. The benefit of testing is further
limited by the nature of
available surveillance and prevention
strategies for these
conditions.
Alzheimer's disease illustrates the potential
for predictive genetic
testing to cause harm. A positive test
is an imprecise measure of
risk and could result in anxiety, stigmatisation,
or discrimination.
Currently such testing would generally
be unethical because no
effective prevention is available.
Such tests will be increasingly available
as the genetic factors that
underpin common diseases are identified,
say the authors.
However, predictive testing must be tailored
to the individual's
needs and preferences, they conclude.
Contact:
James P Evans, Director of Cancer Genetics
Services,
Department of Medicine and Lineberger
Comprehensive Cancer
Center, University of North Carolina,
USA
Email: jpevans@med.unc.edu
(3) WOULD KNOWING
YOUR GENETIC RISK CHANGE
YOUR BEHAVIOUR?
(Genetic risk and behavioural change)
http://bmj.com/cgi/content/full/322/7293/1056
Providing people with genetic information
on risk
may not increase their motivation to change
behaviour, and in
some cases may decrease motivation, finds
a review in this
week's BMJ.
Using the limited evidence and the literature
on behavioural
change, the research team examined if
and how people's
behaviour might be changed when given
DNA based information
about their chances of developing potentially
preventable
diseases such as heart disease and cancer.
The current evidence suggests that providing
people with DNA
derived information about risks to their
health does not increase
motivation to change behaviour beyond
that achieved with
non-genetic information, report the authors.
For instance, since
the introduction of predictive genetic
testing for risk of breast
cancer, no significant changes in screening
behaviour have been
found.
For some people, genetic information may
even reduce
motivation to change behaviour, add the
authors. For example,
parents who tested positive for high cholesterol
levels led to a
sense of fatalism, based on the belief
that genetically conferred
risks are serious and immutable.
Further research is needed to evaluate
programmes in which
genetic risk information is given, including
evaluation of different
ways of giving information, they conclude.
Contact:
Theresa Marteau, Professor of Health Psychology,
Psychology
and Genetics Research Group, King's College
London, UK
Email: theresa.marteau@kcl.ac.uk
(4) GENES AND
ENVIRONMENT IMPORTANT IN
FAMILIES WITH HISTORY OF HIGH CHOLESTEROL
(Mortality over two centuries in
large pedigree with familial
hypercholesterolaemia: family tree
mortality study)
http://bmj.com/cgi/content/full/322/7293/1019
Risk of death varies significantly among
patients with a family
history of high cholesterol (familial
hypercholesterolaemia), with
many untreated patients reaching a normal
life span, finds a study
in this week's BMJ.
This suggests that strong interactions
between genetic and
environmental factors are involved in
this disorder, and
emphasises how much we still have to learn
about the relation
between genes and the environment.
Using official records of births, marriages,
and deaths,
researchers in the Netherlands examined
mortality over two
centuries in a large family with a history
of high cholesterol. They
found that the excess mortality from this
disorder varied over
time. For instance, in the 19th and early
20th century, mortality
was lower than in the general population.
It rose after 1915,
reached its maximum during the 1950s,
and fell thereafter.
During the decades with excess mortality,
survival ranged from
normal life expectancy to severe excess
mortality in different
branches of the family tree.
This large variation of risk suggests that
previous studies, with
families based on selected patients, may
have overestimated
mortality, say the authors. Moreover,
such large variation in
mortality in two directions (over time
and within generations) in a
family indicates that the disorder has
strong interactions with
environmental factors.
Future research is required to identify
patients who are at
extreme risk of premature death, and which
environmental
factors are effective in modulating this
risk, conclude the authors.
Contact:
Eric J G Sijbrands, Department of Vascular
Medicine and
General Internal Medicine, Academic Medical
Centre,
Amsterdam, Netherlands
Email: nrexpert@euronet.nl
(5) PRIMARY CARE
PRACTITIONERS NEED TO BECOME
GENETICALLY LITERATE
(The challenge of integrating genetic
medicine into primary care)
http://bmj.com/cgi/content/full/322/7293/1027
Increasing availability of DNA based tests
and demand by
patients for genetic information and advice
mean that primary
care practitioners will need to become
genetically literate. A
paper in this week's BMJ discusses the
implications of genetic
advances for primary care.
Currently, the most important elements
for primary care are
prediction of risk of certain cancers
and carrier screening for
common conditions such as cystic fibrosis.
Longer term, there
will be increasing use of genetic information
to tailor drug
treatment for a wide range of disorders
and to predict risk of
common conditions such as diabetes and
cardiovascular disease.
Integrating these elements of genetic medicine
into primary care
will require the development of generic
skills in genetic risk
assessment and communication, explain
the authors. A
multifaceted approach - including community
genetic counsellors,
primary care genetic specialists, educational
programmes and
computer support - is essential to support
the procurement of
these skills in primary care, they add.
The authors believe that even if a fraction
of the claims made
about the impending impact of genetics
on clinical practice came
true, clinical genetic services would
be overwhelmed. We must
not miss this opportunity to prepare primary
care for the new
genetics, they conclude.
Contact:
Jon Emery, Clinical Lecturer, Department
of Public Health and
Primary Care, University of Cambridge,
Institute of Public
Health, Cambridge, UK
Email: jde10@medschl.cam.ac.uk
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