Challenges to diagnosing Duchenne

Because Duchenne is rare,¹ healthcare professionals may encounter few cases, if any, during their careers. The rarity of the disease combined with the non-specific early symptoms means diagnosis can be a challenge and may result in diagnostic delay.^2–4

• Average delay in diagnosis (from first symptoms) ranges from 1.3 to ~2.5 years^2,4,5
• Average age at diagnosis is between 4.5 and 4.11 years⁴

Taking appropriate action when concerns first arise may prevent years of uncertainty and stress for families whilst waiting for a diagnosis.^3,6–8

Diagnosing Duchenne: Case study of a 7-year-old boy

Delayed diagnosis of Duchenne muscular dystrophy (DMD) in a 7-year-old boy presenting with delayed speech and muscle weakness
The following case study is based on the case report published in Essex C & Roper H. BMJ. 2000;323:37–38 but the images are for illustrative purposes only.⁹

Challenges 2

24 monthsInitial presentation

At 24 months of age, M was brought to his GP

At 24 months of age, M was brought to his GP because his parents were concerned that he was unable to communicate. He showed no signs of being able to gesture, babble or speak, and had started walking at 23 months.

What would you do?

Speech delay and language impairment should trigger a creatine kinase (CK) test​

Laboratory & genetic tests

M’s GP ordered metabolic and chromosomal tests

M’s GP ordered metabolic and chromosomal tests, which came back normal. A CK test wasn’t carried out.

What would you do?

Developmental delay should trigger a CK test

4 yearsFirst referral

M was referred for a special educational needs assessment

M was referred for a special educational needs assessment, which identified learning difficulties. He was subsequently placed in a school for children with learning disabilities.

What would you do?

Learning difficulties
should trigger a CK test

7.5 yearsSecond referral

M’s younger brother, C, was diagnosed with DMD

M’s younger brother, C, was diagnosed with DMD at the age of 6. Shortly afterwards, M was reassessed by a paediatric neurologist who ordered more laboratory tests.

What would you do?

A family history of DMD and suspicion of abnormal muscle function should trigger a CK test
​

Laboratory tests

M’s serum creatine kinase concentration

M’s serum CK concentration was >10,000 U/L, elevated well above normal levels (normal level: ≤250 U/L).

What would you do?

All patients with elevated CK levels should be referred to a neuromuscular specialist
​

Genetic tests

Genetic testing identified a deletion mutation in the dystrophin gene that included exons

Genetic testing identified a deletion mutation in the dystrophin gene that included exons 3–8.

What would you do?

Genetic testing should be used to determine the specific mutation causing DMD

Diagnosis

At the age of 7 years and 6 months, M was diagnosed with DMD.

At the age of 7 years and 6 months, M was diagnosed with DMD.