WHAT IS DUCHENNE MUSCULAR DYSTROPHY (DMD)?

Duchenne is a rare genetic disorder that affects around 1 in 3,600–6,000 boys.^1–4

Click greyplus in the list below to find out more.

Duchenne is a severe, progressive muscle-wasting disease^1,4–6
Duchenne primarily occurs in males, but can affect females in some cases^2,5
Duchenne is caused by mutations in the dystrophin gene^1,5

Deletion, duplication, nonsense and other small mutations can cause Duchenne^7–9
With no functional dystrophin, muscle cells degenerate¹⁰

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THE SIGNS OF DUCHENNE CAN BE DIFFICULT TO DETECT¹¹

This, combined with the rarity of the disease and non-specific early symptoms, means that diagnosis can be delayed by an average of 2 years.^4,11,14

Reducing diagnostic delay is important, because early detection can mean:

Early interventions, which may slow the course of the disease and extend survival^4,5,15

Enrolment in research-based registries and clinical trials⁴

Opportunities for genetic counselling and family planning^4,5

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WHEN TO SUSPECT DUCHENNE⁵

Positive family history
+
suspicion of abnormal muscle function

Developmental delay, such as not walking by 16–18 months, Gowers’ sign or toe walking

Unexplained increase in transaminases

Unsure of how to recognise developmental delay or abnormal muscle function?

Use the red flag checklist

Red flag checklist

^{Adapted from Birnkrant DJ, et al. 2018⁵}

PLEASE LISTEN TO CAREGIVER CONCERNS

Caregivers who are worried about their child's development are correct more than 80% of the time*¹⁶

^{*Refers to identification of developmental and behavioural problems}

WHAT TO DO IF YOU SUSPECT DUCHENNE

SCREEN, THEN REFER TO SPECIALIST CARE

Elevated creatinine kinase levels reflect muscle damage

Order a creatine kinase (CK) blood test

This is a simple and rapid way to screen for elevated creatine kinase (CK) levels – which reflect muscle damage^4,17

Find out when to order a CK test and what the results mean

Refer to a neuromuscular specialist

A genetic diagnosis is required to confirm Duchenne and identify the specific mutation causing the disease⁵

Find out when to refer to a neuromuscular specialist

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PROMPT REFERRAL IS VITAL TO GIVE YOUR PATIENTS THE BEST CHANCE OF BETTER OUTCOMES^4,5

A neuromuscular specialist can then:⁵

Prompt referral to a neuromuscular specialist can lead to better treatment outcomes in your patients

Test creatine kinase (CK) levels⁵

CK is an enzyme found in skeletal muscle and other tissues. Elevated CK levels reflect muscle damage²⁷

Identify the child’s exact mutation⁵

Genetic testing can identify the mutation and confirm the diagnosis⁵

Define best management options⁵

Timely treatment may help delay disease progression⁵

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If you are not a Healthcare Professional, visit Duchenne and You for more information on signs and symptoms and support following a Duchenne diagnosis.

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Duchenne is a severe, progressive muscle-wasting disease^1,4–6

Children with Duchenne suffer with progressive muscle deterioration and an ongoing decline in physical function.^1,4–6

Muscle weakness becomes apparent in early childhood, and, on average, patients require a wheelchair by the early teenage years.^1,4

Ultimately, respiratory and cardiac failure lead to an early death.^4,5

^{Adapted from Birnkrant et al. 2018 part 1, Bushby et al. 2010; Goemans et al. 2014; Sussman 2002 and van Ruiten et al. 2014^1,2,4,5,18}

Duchenne primarily occurs in males, but can affect females in some cases^2,5

Duchenne is caused by mutations in the dystrophin gene^1,5

Mutations in the dystrophin gene lead to the absence of, or defects in, dystrophin – an important component of the muscle cell membrane.^1,5

Duchenne is caused by mutations in the dystrophin gene

^{Adapted from Muscular Dystrophy Association²⁰}

Learn more about dystrophin

Dystrophin acts as a shock absorber in muscle²¹

It helps prevent damage by providing stability and structure to the muscle fibre and membrane when muscles contract.^10,21

This allows muscle cells to return to their initial state after stress.²¹

Deletion, duplication, nonsense and other small mutations can cause Duchenne^7–9

The dystrophin gene is located on the X chromosome and is the largest gene in the human genome.⁷ This may make it more susceptible to mutations.²²

^{Adapted from Nowak et al. 2004 and Bladen et al. 2015^7,23}

So far, more than 7,000 individual mutations in the dystrophin gene have been identified.⁷

Dystrophin gene mutations

Deletion, duplication, nonsense and other small mutations can cause Duchenne

^{Adapted from Bladen et al. 2015, Pichavant et al. 2011 and Kalman et al. 2011^7–9}

Why mutation type matters

It is important to know each patient’s specific mutation, because targeted therapies are being investigated.^5,9

Large mutations can be detected using multiplex ligation-dependent probe amplification (MLPA). Small deletions, such as nonsense mutations, require gene sequencing.⁹

Learn more about genetic testing

With no functional dystrophin, muscle cells degenerate¹⁰

Gradually, muscle is replaced with fat and fibrous connective tissue.^10,24,25

T₁ weighted magnetic resonance images of thigh muscle as DMD progresses over time²⁴

brain

^{Adapted from Sweeney 2014²⁴}

Elevated CK usually means muscle damage²⁷

CK is an enzyme found in skeletal muscle as well as in the heart, brain and other tissues. Increased amounts of CK are released into the blood when there is muscle damage.²⁷

You should order a CK test if a patient has:⁵

Unexplained elevated transaminases (AST and ALT)
A family history of Duchenne and suspected abnormal muscle function
Developmental delay, such as not walking by 16–18 months, Gowers’ sign or toe walking

WHAT THE RESULTS MEAN^5,28

refer

*Elevated CK levels of approximately ≥500 U/L, even if symptomatic, require further assessment and should be followed up.²⁸ CK levels >2000 U/L should prompt further investigation for DMD.²⁸

Refer all patients with elevated CK or missed motor milestones^27,28

All patients who have elevated CK levels should be immediately referred to a neuromuscular specialist.^27,28

Normal or mildly elevated CK does not rule out neuromuscular disease. If a patient has missed motor milestones, they should also be referred to a neuromuscular specialist.²⁷

A prompt referral for diagnosis is vital to give your patients the best chance of better clinical outcomes^4,5
Timely interventions may help delay disease progression^4,5,29,30

‘Red flags' checklist

This tool provides a comprehensive checklist to help identify early signs or symptoms of neuromuscular disease.

0–4 months

Cannot hold head up when on tummy at 2 months^1,2
Not rolling over by 4 months¹
Not making sounds by 4 months²

6–9 months

Not reaching for objects by 6 months¹
Cannot sit without support at 6–9 months^1–3
Not crawling by 9 months¹
Not taking weight on legs while supported²
Cannot pick up small objects at 9 months¹
Not making vowel sounds at 6 months (‘ah’, ‘eh’, ‘oh’), does not babble at 9 months²

12–18 months

Not walking by 16–18 months^3,4
Does not perform play activities such as building with blocks by 18 months¹
Difficulty in gripping, for example, not holding or scribbling with crayons by 18 months¹
Not speaking first word by 12 months²
Does not have at least 6 words by 18 months²

2–3 years

Not jumping¹
Cannot climb stairs (alternate feet)^1,2
Cannot run, or runs with difficulty^2,3
Cannot climb on and off furniture¹
Difficulty making or copying a straight line or circle¹
Not speaking in sentences by 3 years²

Other early signs and symptoms may include:^4,5

Gowers’ sign (pushing on floor and ‘climbing’ on legs to achieve a standing position)
Waddling gait
Enlarged calves
Inability to keep up with peers

^{Adapted from references 1–5.

References: 1. Noritz GH, et al. Pediatrics. 2013;131:e2016–e2027. 2. CDC developmental milestones. Available at: https://www.cdc.gov/ncbddd/actearly/milestones/index.html. [accessed April 2019].
3. Lurio JG, et al. Am Fam Physician. 2015;91:38–44. 4. Birnkrant DJ, et al. Lancet Neurol. 2018;17:251–267 [Part 1]. 5. Ciafaloni E, et al. J Pediatr. 2009;155:380–385.}

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action

DO NOT WAIT
If you see two or more red flags, refer your patient to a neuromuscular specialist. Get more information here

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WHAT IS DUCHENNE MUSCULAR DYSTROPHY (DMD)?

THE SIGNS OF DUCHENNE CAN BE DIFFICULT TO DETECT¹¹

WHEN TO SUSPECT DUCHENNE⁵

PLEASE LISTEN TO CAREGIVER CONCERNS

WHAT TO DO IF YOU SUSPECT DUCHENNE

Order a creatine kinase (CK) blood test

Refer to a neuromuscular specialist

PROMPT REFERRAL IS VITAL TO GIVE YOUR PATIENTS THE BEST CHANCE OF BETTER OUTCOMES^4,5

Test creatine kinase (CK) levels⁵

Identify the child’s exact mutation⁵

Define best management options⁵

Duchenne is a severe, progressive muscle-wasting disease^1,4–6

Duchenne primarily occurs in males, but can affect females in some cases^2,5

Duchenne is caused by mutations in the dystrophin gene^1,5

Dystrophin acts as a shock absorber in muscle²¹

Deletion, duplication, nonsense and other small mutations can cause Duchenne^7–9