So, the Human Fertilisation and
Embryology Authority (HFEA) will review the list of
approved inherited conditions for which preimplantation genetic diagnosis (PGD) is currently licensed.
As related by Professor Alan Handyside and colleagues at The Bridge
Centre in an earlier BioNews, seven disorders, of which Marfan syndrome is one, have been
selected for review.
The logic runs that as treatment and quality of life improve for
people with these conditions, so afflicted families should have less
entitlement to publicly funded PGD, which aims to prevent affected children being
born.
I do not write to query that logic. I write to say that the HFEA must
maintain its support for PGD
in the case of Marfan syndrome.
Marfan syndrome is not curable. It
begins at conception and by the time the infant is born there are already severe
manifestations which will last a lifetime. These will not only affect the
lifespan, but the quality of life.
Yes, lifespan is slowly improving due
to improved medication (beta-blockers in particular) and surgery. However, my
first contact with many of the families I see will be subsequent to a sudden
unexpected death. There is insufficient awareness of Marfan syndrome so not all
- or even the majority - of cases are diagnosed or treated.
Marfan syndrome has been calculated
to affect one in 3,330 in Europe. By this estimate there should be 18,000 known
Marfan syndrome cases in the UK. At a stretch, we know of approximately 9,000. Where
are the rest? These are the ones who go undiagnosed and die suddenly.
These people may have also had families
by the time they die suddenly so that the genetic defect is perpetuated in the
gene pool. Moreover, 25 percent of cases are the result of de novo mutations - in other words the mutation occurs spontaneously at conception with no family history of the disease. These
are usually more severe than the familial cases. Such people now benefit from
more effective therapy, including surgery, and are therefore more likely to
live into fertility. Their children have a 50 percent likelihood of inheriting this
most severe form of the disease.
These patients should be allowed to start
families free of the disease by using PGD. Without access to PGD, many will
choose to remain childless.
Quality of life remains severely affected
by the multi-system nature of Marfan syndrome. Patients do not just have
dislocated lenses and aortic aneurysms to contend with. Their eyes may be affected
by severe short-sightedness, by retinal detachment, and glaucoma.
The skeleton suffers from patients' excessive
height for which we have no effective therapy. There are chest bone
abnormalities, loose painful joints, scoliosis (often requiring surgery) and
early, and very painful, osteoarthritis so that old age really starts around age 50.
With regard to the heart, as well as running
the risk of fatal aortic dissection, patients suffer from prolapse of the heart
valves, left ventricular failure, and endocarditis. Forty percent of patients
have arrhythmias. So as well as dying at an early age, patients have very
difficult lives. I hardly need mention the burden on the NHS.
Our research has also uncovered
irritable bowel syndrome in 20 percent of cases, dental problems such as
impacted teeth, and psychological problems such as depression, isolation and
poor self-image.
Researchers and clinicians are
working as quickly as we can (one major trial will publish its results in 2018)
to find improved therapies in the form of losartan or irbesartan. There are 10
trials running internationally. Patients are enthusiastic about joining in,
because they know how awful this condition is.
In short, Marfan syndrome is a
terrible disease. Families must have access to PGD to limit the genetic impact
on their families in the future.
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