Duchenne Muscular Dystrophy: An Australian Guide

Duchenne muscular dystrophy: the three years before anybody tests

In the Australian study that established how common Duchenne muscular dystrophy is in New South Wales and the ACT, the researchers recorded two ages.

Parents first raised concerns at a mean age of 1.8 years.

Diagnosis came at a mean age of 4.8 years.

Three years. In a condition where corticosteroids slow the loss of muscle and prolong walking, where cardiac medication is started prophylactically, and where every month of preserved strength is a month that is not coming back. Gross motor delay was what prompted presentation in 57 per cent of cases, which means more than half of these families went to a doctor because their son was not moving properly, and then waited three years.

The test that would have answered it is a creatine kinase (CK) blood test. It costs almost nothing, any pathology lab in the country runs it, and in Duchenne it comes back ten to a hundred times the normal level. There is no clinical scenario in which a boy with unexplained motor delay should not have one.

That is the single most useful thing in this guide and it is why it goes first.

The rest covers what Duchenne is, how the diagnosis is made, the trajectory as it now stands, treatment including what the steroids actually do, the surveillance schedule, and what families should be arranging and when. Adult life with Duchenne is a large enough subject that it has its own guide, and it is the one most worth reading if the person is over sixteen.

What Duchenne is

The gene. DMD, on the X chromosome, which makes a protein called dystrophin. It is one of the largest genes in the human genome.

What dystrophin does. It anchors the internal skeleton of a muscle fibre to the membrane and the surrounding tissue, so that when the fibre contracts, the force is transmitted without tearing the membrane. Without it, ordinary contraction damages the fibre.

Duchenne versus Becker. In Duchenne, dystrophin is effectively absent. In Becker muscular dystrophy, the same gene is affected but some partially functional dystrophin is still made — so the course is slower and milder, sometimes much milder. The distinction is made on the specific variant and on dystrophin levels, and it matters enormously for prognosis. See Becker, limb-girdle and FSHD.

Inheritance. X-linked recessive. Boys have one X chromosome, so a single faulty copy produces the condition. Girls have two, so a faulty copy usually produces a carrier rather than an affected person — though female carriers are not symptom-free, and carrier women need cardiac surveillance of their own, covered in families, carriers and genetics.

And a figure that surprises most families: in the Australian cohort, 39.6 per cent of cases arose from a new mutation — the mother was not a carrier. Which means roughly two in five families with a son diagnosed with Duchenne have no inherited risk behind them and no family history to have warned them.

Incidence. The Australian study found a cumulative incidence of 19.7 per 100,000 male live births, about 1 in 5,076, for males born between 2002 and 2012 in NSW and the ACT. Australian birth prevalence estimates across four studies range from 18.6 to 22.7 per 100,000. Incidence has been essentially stable for about forty years.

The signs, and what they look like at home

Duchenne does not usually announce itself as weakness. It announces itself as a child who moves differently.

Walking late, or walking normally and then seeming to go backwards.

Falling a lot, more than other children the same age, and tripping over nothing.

Trouble with stairs, pulling on the rail, taking them one at a time, or avoiding them.

Trouble getting up from the floor. The classic sign is the Gowers manoeuvre — turning onto the front, pushing up onto hands and knees, then “walking” the hands up the thighs to get upright, because the hip and thigh muscles cannot do it directly. If your son does this, mention it by name.

Walking on tiptoes, or a waddling gait with the belly pushed forward.

Large, firm calves. Called pseudohypertrophy — the muscle looks bigger because it is being replaced by fat and fibrous tissue. Parents often notice this as their son having “footballer’s calves.”

Difficulty running or jumping, or never really learning to.

Tiring quickly, wanting to be carried, not keeping up.

Speech delay or learning difficulties in a subset, because dystrophin is also expressed in the brain.

And one that is easy to miss: raised liver enzymes on an unrelated blood test. ALT and AST are released by damaged muscle as well as liver, so a child investigated for a suspected liver problem sometimes turns out to have a muscle one. If a boy has unexplained raised transaminases, a CK test is the next step.

What it is misdiagnosed as: cerebral palsy, global developmental delay, clumsiness, hypermobility, autism where there is also speech or behavioural difference, and — frequently — nothing at all, with the family told he will grow out of it.

Getting the diagnosis

The CK test first. Enormously elevated in Duchenne, usually in the thousands to tens of thousands. A normal CK essentially rules it out. This is the gatekeeping test and it does not require a specialist to order.

Then genetic testing. In the Australian cohort, genetic confirmation was available in 104 of 107 cases (97 per cent). MLPA — which detects deletions and duplications — found the variant in 75 per cent of confirmed cases, with DNA sequencing needed in a further 15.4 per cent. Only three children in the whole cohort required a muscle biopsy. Which is worth knowing, because older material describes biopsy as routine and it no longer is.

Why the specific variant matters. It determines whether mutation-specific therapies could ever apply, it informs the Duchenne-versus-Becker question, and it is what allows carrier testing in female relatives. Get the exact variant in writing.

Then a neuromuscular clinic, and from there the whole surveillance structure.

What to ask for at diagnosis: the variant in writing; referral to a paediatric neuromuscular service; baseline cardiac assessment; a physiotherapy and occupational therapy assessment; genetic counselling for the family; a conversation about corticosteroids and their timing; and a referral to your state muscular dystrophy organisation, several of which are registered NDIS providers.

And the NDIS application, immediately. Duchenne muscular dystrophy is named on NDIS List B. See muscular dystrophy and the NDIS.

The trajectory as it now stands

This is where honesty is important, because the older material describes a condition that modern treatment has substantially altered.

Early childhood. Motor delay, the signs above, diagnosis.

The ambulatory years. Walking, with increasing difficulty, falls, fatigue, contractures beginning at the ankles. Corticosteroids are started during this phase and prolong it. Physiotherapy, stretching, night splints, and a powered wheelchair introduced for distance before it is needed full-time — which is not a defeat, it is energy conservation.

Loss of ambulation. Historically around 9 to 11 years; with corticosteroids, typically later. This transition brings scoliosis risk, a change in equipment needs, and an increase in the importance of respiratory and cardiac surveillance.

The non-ambulatory years. Upper limb function declines gradually. Scoliosis may require surgery. Respiratory function falls and nocturnal ventilation is started on defined thresholds. Cardiac function is monitored and treated. Hand function is preserved for a long time and is worth protecting, because it is what operates a wheelchair, a phone and a computer.

Adulthood, which is the part the system has not caught up with. See Duchenne into adulthood.

And the survival figures, from the Australian 50-year cohort study of 356 males published in The Lancet Regional Health – Western Pacific in 2025:

Over the same five decades, corticosteroid use, ACE inhibitor use, echocardiography and respiratory support all increased, and people receiving those interventions had longer life expectancy. Mean age at diagnosis fell from 6.4 to 3.4 years.

A word about what those numbers mean for an individual. They are medians across birth cohorts, and the most recent cohort with complete follow-up was born in the 1990s — which necessarily excludes everybody born since, who have had steroids earlier, ventilation earlier and cardiac protection from childhood. A boy diagnosed in Australia in the 2020s is not described by a figure drawn from men born thirty years ago. Nobody can tell you what his number is. What is reasonable to say is that the trajectory has been moving in one direction for fifty years and the interventions driving it are now standard.

Corticosteroids: what they do and what they cost

The biggest decision in Duchenne care, and the one families most want straight information about.

What they do. Prednisolone or deflazacort slow the loss of muscle strength and prolong walking. The Australian cohort found longer life expectancy in those who used them. This is the single most effective intervention available in Duchenne and declining it has consequences.

What they cost. Real side effects, which are managed rather than avoided:

Bone fragility, which is the serious one. The 2018 DMD care considerations report that 20 to 60 per cent of boys with Duchenne sustain low-trauma limb fractures and up to 30 per cent have symptomatic vertebral fractures — and that steroid-treated boys had a long-bone fracture rate around 2.6 times that of boys never treated. This requires active monitoring, not just awareness: baseline spine imaging for everybody, repeated every one to two years on steroids, annual spine DXA and vitamin D, and intravenous bisphosphonates as first-line treatment for moderate or severe vertebral fractures even when they are not causing symptoms.

Weight gain, which matters mechanically as well as metabolically.

Growth suppression and delayed puberty, which needs endocrine involvement.

Behavioural effects — irritability, mood change — frequently most pronounced in the first weeks and with a daily dosing pattern.

Adrenal suppression, which means a boy on long-term steroids needs stress dosing during illness or surgery and an alert card. Families should know this and so should any support worker.

Cataracts, blood pressure, glucose intolerance, immune suppression.

On deflazacort specifically: the 2018 guidance notes that earlier claims of a bone-sparing advantage over prednisolone are doubted, since fractures remain frequent in deflazacort-treated boys.

How to approach the decision. With a neuromuscular clinic, with the side-effect monitoring plan in place before starting rather than afterwards, and with the understanding that the regimen can be adjusted — dose, schedule, and which drug — if side effects are a problem. Stopping is usually not the right answer to a side effect; changing the regimen frequently is. See steroids, bones and scoliosis.

The surveillance schedule

Duchenne is a condition where the surveillance is the treatment, because the organs that fail are monitored and medicated before they cause symptoms. From the 2018 international care considerations:

Cardiac. Baseline assessment at diagnosis with ECG and non-invasive imaging. Echocardiography until about age 6 or 7, then cardiac MRI, which can usually be done without anaesthesia from that age. Annual assessment until 10, then at least annually in asymptomatic patients. ACE inhibitors or ARBs recommended by age 10, before any symptom, with earlier use at cardiologist discretion. Started at any age once heart failure symptoms or imaging abnormalities appear. Consider annual Holter monitoring once left ventricular dysfunction or fibrosis develops. See the heart and muscular dystrophy.

Respiratory. Spirometry from age 5 to 6. FVC annually while walking, every six months once not walking, with MIP, MEP, peak cough flow and oxygen saturation. CO2 monitoring every six months in non-ambulatory patients. Lung volume recruitment from FVC 60 per cent predicted or less. Assisted coughing from FVC below 50 per cent predicted, peak cough flow below 270 L/min, or MEP below 60 cm H2O. Nocturnal ventilation on symptoms, an abnormal sleep study, or FVC below 50 per cent. Most or all core respiratory therapies should be in use by 18 to 21. See breathing and muscular dystrophy.

Spine. Visual inspection at least annually while walking; every six months in the early non-ambulatory stage, with a radiograph when the boy first becomes non-ambulatory. Orthopaedic referral at 20 degrees or more. Spinal orthoses are not recommended. Cardiology and respiratory consultation before any spinal surgery.

Bone. Baseline lateral thoracolumbar spine radiograph for everybody, repeated every one to two years on steroids. Annual spine DXA, vitamin D and calcium intake review.

Vaccination. Annual inactivated influenza vaccine, not the live nasal form, plus pneumococcal vaccination.

The practical point: this is a schedule, and in a busy clinic things fall off it. Keep your own copy, know which assessment is due when, and ask. Families who track the schedule get the schedule delivered.

What to arrange, and roughly when

At diagnosis. NDIS application. Genetic counselling for the family, including carrier testing for the mother and discussion with the wider maternal family. Neuromuscular clinic referral. Physiotherapy for stretching and contracture prevention — starting before there are contractures. Occupational therapy. Your state MD organisation.

Early childhood. Steroid discussion with the monitoring plan. Cardiac baseline. Physiotherapy routine embedded at home. School conversation, including that a subset of boys have learning difficulties and may need assessment and support.

Before mobility becomes limited. A powered wheelchair for distance, specified early. Home access assessed — ramps, doorways, the bathroom. This is where lead times bite, and the single most common error is waiting until something is needed. See equipment and home modifications.

Around loss of ambulation. Seating reviewed properly, scoliosis surveillance stepped up, respiratory assessment frequency doubled, hoist and transfer planning, bathroom modification if not already done.

Mid-teens. This is when transition planning should start, not at 18. Adult neurology, adult respiratory, adult cardiology, adult GP. See Duchenne into adulthood.

And throughout: hand function, posture and pain. Three things that get less attention than they deserve and that determine the quality of a day more than almost anything else.

School, and the things worth setting up early

For a boy diagnosed at three or four, school is where the next fourteen years of practical work happens, and it goes well or badly depending almost entirely on how well the school understands what it has.

Tell them what it means functionally, not just the name of the condition. Progressive. Fatigue that is physiological rather than motivational — a boy who sits down in the playground is not being lazy. Fine motor decline that will affect handwriting. Falls risk, with fracture risk elevated by the steroids. Toileting and personal care needs that will grow. And, in a subset, genuine learning differences: dystrophin is expressed in the brain, and learning difficulties, autism and ADHD occur at higher rates than in the general population, so an assessment is reasonable rather than alarmist.

Ask for a formal individual education plan with funded adjustments, reviewed each term rather than annually, because the condition moves faster than an annual cycle.

Get the therapists into the school, not only the clinic. An occupational therapist and physiotherapist who have walked the corridor, seen the toilet and watched the playground solve problems a clinic appointment cannot.

Anticipate the handwriting transition. Typing, then voice input, taught before handwriting fails rather than after. Exam provisions — extra time, a scribe, a computer, rest breaks — documented well before the exams that count.

Modify physical education rather than exempting him from it. Participation in some form keeps him in the group; a blanket exemption removes him from it. Same with excursions and camps, which are worth arranging properly rather than accepting as impossible.

Plan toileting and personal care honestly, with a named person, a private space and a written plan. This is what boys themselves worry about most and what adults discuss least.

Tell every new teacher, every year, in a short written note. Institutional memory is worse than anybody expects.

And protect the friendships above the grades. A boy whose social life is intact has a better adolescence than one whose marks are, and school friendships are also what make the years after school survivable. See Duchenne into adulthood.