Is Duchenne muscular dystrophy always inherited?
No.
You might think that each person with a Duchenne gene has inherited
this gene from a parent. But in fact, the Duchenne gene can occur in a
child without anyone else in the family having the gene. This happens
if the faulty gene is made when the child's cells are being formed,
without the mother's cells being affected. It means that about half the
children with Duchenne muscular dystrophy will not have family members
carrying the gene.
DNA testing and specialist genetic advice can
help to find out whether the Duchenne gene is carried by other members
of the family.
What are the symptoms of Duchenne muscular dystrophy?
The symptoms usually start around age 1-3 years. Parents may notice difficulties with:
- Walking,
running, jumping and climbing stairs. Walking may look different with a
'waddling' type of walk. The boy may be late in starting to walk
(although many children without Duchenne muscular dystrophy also walk
late).
- When you pick the child up, you may feel as if he 'slips through
your hands', due to looseness of the muscles around the shoulder.
- The muscles may look bulky, even though they are not strong. This is often seen with the calf muscles.
- As he gets older, the child may use his hands to help him get up,
looking as if he is 'climbing up his legs'. This is called 'Gower's
sign'.
- Some boys with Duchenne muscular dystrophy also have a learning
difficulty. Usually this is not severe. Also, it is not progressive (it
does not increase).
- Sometimes, a general delay in development shows up before the
muscular dystrophy is diagnosed. If you have a boy whose development is
delayed, you may be offered a screening test for Duchenne muscular
dystrophy. This would be the 'creatinine kinase' blood test (see
below). But remember that there are many other causes of developmental
delay.
How is Duchenne muscular dystrophy diagnosed?
The
diagnosis may be suspected because of the child's symptoms, and by
observing his walking and movements. Your doctor may examine the child
to check his muscle strength and look for signs of any other condition.
Tests are needed for a definite diagnosis. These are:
-
A blood test for creatinine kinase:
Patients with Duchenne muscular dystrophy have a very high level of a
substance called 'creatinine kinase' or 'CK' in the blood (about ten
times the normal level or more). If the creatinine kinase level is
normal, then the child does not have Duchenne muscular dystrophy. But
if the level is high, other tests are needed to see whether this is due
to Duchenne muscular dystrophy or to some other condition.
-
A muscle biopsy: This involves taking a small sample of a
muscle, under local anaesthetic. The sample is examined under a
microscope using special techniques to look at the muscle fibres and
the dystrophin protein.
-
DNA testing: This is done using a blood sample. The DNA in
the blood is tested to look at the dystrophin gene. This test can
diagnose most cases of Duchenne muscular dystrophy. However, some cases
will not show up on DNA testing, which is why the other tests are also
used.
Advice from a genetic specialist
You and
your child may be referred to a doctor who specialises in diagnosing
genetic conditions (a 'geneticist'). This type of advice is also called
'genetic counselling'. Genetic advice is useful if you want to know
whether anyone else in the family is carrying the Duchenne gene. This
information is particularly important if you are considering having
more children, because you may want to know what is the chance that
another child could inherit the Duchenne gene.
If a mother has
the Duchenne gene and has another pregnancy, it may be possible to do a
prenatal test. This would test whether the unborn baby has the Duchenne
gene. A geneticist can give you more information about this option.
What else could it be?
If muscle weakness is
the problem, this could also be due to other causes, for example: other
types of muscular dystrophy, a 'myopathy' (which is a different type of
muscle weakness, which can be temporary or permanent) or a neurological
disorder (which affects the nerves controlling the muscles).
If the problem is a young boy with delayed walking or delayed development, there are many other possible reasons for these.
If
the query concerns a blood test showing raised creatinine kinase, there
are various reasons why this can occur, including other types of
muscular dystrophy and some muscle injuries. The actual level of the
creatinine kinase, plus other tests, can help to decide what the cause
is. The creatinine kinase level in Duchenne muscular dystrophy is
always extremely high (ten times normal levels or more).
Usually
a diagnosis can be made by taking into account the whole picture - both
the pattern of symptoms and the results of the tests. If the results
are unclear, it may suggested that you see a doctor who specialises in
neuromuscular or genetic conditions.
What is the treatment for Duchenne muscular dystrophy?
There
isn't a cure for muscular dystrophy at present. However, there are
treatments which can help. This is an outline of the treatments you may
be offered:
Information and support
You may need
information or support from organisations and parents who have
experience of Duchenne muscular dystrophy. See the further information
section for suggestions.
Monitoring and general treatment
It is
useful to see a specialist "team" of healthcare staff who have
experience treating muscular dystrophy. You may see various doctors,
nurses or therapists who each have different expertise. This is because
the child may need more than one type of treatment. The aim is to have
a teamwork approach, to make sure that everyone works together. Usually
the child will be offered regular monitoring, so that if there are
problems they can be found and treated as early as possible.
A
fairly new treatment for Duchenne muscular dystrophy is
'corticosteroid' treatment, using medicines such as prednisolone or
deflazacort. These help to keep the muscles strong. Research has shown
that this treatment can slow down the progression of muscle weakness -
though it will not cure the problem. Corticosteroids can have side
effects, so the treatment needs monitoring. The best time to start
corticosteroids needs to be discussed with a specialist, who may
monitor the child's muscle strength over a period of time, to help
decide when to start this treatment.
Keeping up good general
health is important. So you may be advised about things like nutrition,
and how much exercise is best for the child.
Treatment in early childhood (preschool age)
At
this stage of childhood, Duchenne muscular dystrophy is usually mild.
Physiotherapy is useful to help keep the joints and muscles supple.
Sometimes night-time splints can help to prevent the ankle joint
becoming tight.
Treatments for age 5-9 years
At this age,
some support may be needed for the legs and ankles. This is usually
night time ankle splints, or sometimes longer braces The ankle joints
may become tight with 'contractures' (see below) and an operation can
help to release the tight areas around the joint.
9 years onwards
At some time after the age
of 8 years, the leg muscles become significantly weaker, so that
walking gradually gets more difficult, and a wheelchair is needed. The
age at which this happens varies from person to person. Often it is
around age 9-11 years, although with corticosteroid treatment, some
boys can walk for longer.
After the boy starts needing a
wheelchair, this is also the time that complications may start, so it
is important to monitor the boy's health and to treat any complications
early (see below).
Emotions and stress: It isn't always easy
being a teenager at the best of times, and having a serious illness
means there is more to cope with. Sometimes counselling can be useful,
for the child or their family, or both. Support is also available from
muscular dystrophy support groups - see further information below.
Practical
support may be needed for equipment, care, holidays and breaks. Local
health services and care services can help. Certain charities may
provide equipment, funding or holidays.
What are the complications of Duchenne muscular dystrophy, and how can they be treated?
Muscle and joint problems
Contractures
(tightness around the joints) or scoliosis (curvature of the spine) can
occur as a result of muscle weakness. Surgery can be used to treat
these.
Chest and breathing problems
During the teenage years, the breathing muscles weaken, causing shallow breathing. This can lead to:
Chest
infections, which are harder to clear. Chest infections need treating
promptly with antibiotics, and chest physiotherapy helps to clear mucus
from the chest. Immunization with influenza (flu) and pneumococcal
vaccines is advised, to help prevent chest infections.
Shallow
breathing can cause poor sleep and tiredness. This can be helped in
various ways, using physiotherapy and/or equipment. The equipment gives
oxygen or provides a higher air pressure to assist breathing. Although
this might sound complicated, there are ways of giving breathing
support which give less interference with everyday life. For example,
it the equipment may only be needed at night, and can use simple
devices which fit easily on the mouth or nose to assist breathing.
Later
on, as the muscle weakness progresses, more support will be needed for
breathing. The treatment of breathing problems has improved over recent
years, and this has helped to improve wellbeing and outlook for people
with Duchenne muscular dystrophy.
Heart problems
Teenagers and adults with
Duchenne muscular dystrophy may develop a heart problem. This is called
'cardiomyopathy' and is due to weakness of the heart muscle. It may
cause symptoms such as tiredness, leg swelling, shortness of breath or
an irregular heart beat. These symptoms can be helped by medication.
The medication seems to work best if started at an early stage, before
there are any symptoms. Heart tests such as an ECG (recording of the
heart) and 'echo' (ultrasound) can be used to detect cardiomyopathy at
this early stage. So people with Duchenne muscular dystrophy should
have regular heart checkups with a specialist, starting from early
childhood.
Anaesthetics
People with Duchenne muscular
dystrophy need extra care if they have a general anaesthetic. Certain
anaesthetic medicines can cause a harmful reaction for people who have
Duchenne muscular dystrophy. Also, extra care for the chest and
breathing is needed. If an anaesthetic is needed, assessment by a
senior anaesthetist is important, and extra supervision will be
necessary during and after the operation.
Nutrition and digestion
Constipation is a
common problem for anyone who is not mobile, including older children
who have Duchenne muscular dystrophy. This can be treated with
laxatives.
Boys with Duchenne muscular dystrophy are at risk of
low bone density, which can lead to osteoporosis. Vitamin D and calcium
help to prevent this. These can be obtained from certain foods or from
calcium and vitamin D supplements. Vitamin D also comes from sunshine
on the skin.
Weight loss or weight gain is sometimes a problem.
Excess weight gain can be due to lack of mobility or to corticosteroid
treatment. Weight loss can happen if there are a lot of chest
infections. Advice from a dietician is useful, and vitamins or
supplements can help for someone who is underweight.
What is the outlook for Duchenne muscular dystrophy?
This
is a serious condition and it does shorten life. Because the muscle
weakness increases gradually over the years, complications eventually
develop. The breathing or heart problems usually become more serious
for older teenagers or people in their twenties. Without treatment,
most people with Duchenne muscular dystrophy do not live beyond their
early twenties. Good treatment can make a difference to both wellbeing
and the length of life, and may lengthen life up to the person's late
twenties.
What about people who carry the gene?
Girls
and women who carry the Duchenne gene are usually well and have no
symptoms of the condition. Some women with the Duchenne gene do have a
slight muscle weakness themselves, but it is mild enough not to affect
their everyday lives.
Women carrying the Duchenne gene do have a
risk that the condition will be passed on to their children. Usually,
there is a 1 in 2 chance that a boy child will have Duchenne muscular
dystrophy, and a 1 in 2 chance that a girl child will carry the gene.
Prenatal diagnosis during pregnancy may be possible. It is helpful to
see a genetic specialist who can give more precise information about
your own particular situation.
Rarely, women who carry the
Duchenne gene may develop a heart problem, cardiomyopathy - which is
explained above in the complications section. For this reason, some
doctors recommend that women who have the Duchenne gene have a heart
check every five years, starting at around age twenty. Reassuringly,
research from the UK found that most women with the Duchenne gene had
only very minor changes found on heart checkups. Also, recent research
found that there was no difference in life expectancy between women
carrying the Duchenne gene and those without the gene.
Might there be any new treatments in future?
There
are some ideas, but these are still at the research stage.
Possibilities include taking a protein called utrophin, which is
similar to the protein dystrophin - the one that is lacking in Duchenne
muscular dystrophy. Gene therapy (to replace the faulty part of the
gene) is another area of research.
Further help and information
The Muscular Dystrophy Campaign
61 Southwark Street, London SE1 0HL
Helpline: 0800 652 6352
Web: www.muscular-dystrophy.org
This is a UK charity for all muscular dystrophies, neuromuscular
disorders and related conditions. It funds research, offers support and
advice, and provides information.
References
-
Muscular Dystrophy Campaign: Duchenne muscular dystrophy 'about' page
-
Manzur A, Kuntzer T, Pike M, et al;
Glucocorticoid corticosteroids for Duchenne muscular dystrophy.
Cochrane Database Syst Rev. 2008 Jan 23;(1):CD003725. [abstract]
-
No authors listed;
Cardiovascular health supervision for individuals affected by Duchenne
or Becker muscular dystrophy. Pediatrics. 2005 Dec;116(6):1569-73.
[abstract]
-
Chakkalakal JV, Thompson J, Parks RJ, et al;
Molecular, cellular, and pharmacological therapies for Duchenne/Becker
muscular dystrophies. FASEB J. 2005 Jun;19(8):880-91. [abstract]
-
Grain L, Cortina-Borja M, Forfar C, et al;
Cardiac abnormalities and skeletal muscle weakness in carriers of
Duchenne and Becker muscular dystrophies and controls. Neuromuscul
Disord. 2001 Mar;11(2):186-91. [abstract]
-
Holloway SM, Wilcox DE, Wilcox A, et al;
Life expectancy and death from cardiomyopathy amongst carriers of
Duchenne and Becker muscular dystrophy in Scotland. Heart. 2007 Oct
11;. [abstract]
© EMIS and PiP 2008 Updated: 21 Feb 2008
