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A 30-minute case-based webinar on the pediatric presentation and early diagnosis of metachromatic leukodystrophy (MLD). Dr Simon Jones, a metabolic paediatrician in Manchester, uses two real cases � one late-infantile, one early-juvenile � to show how MLD first hides behind everyday concerns such as flat feet, in-toeing, dyspraxia and school difficulties, and why simple clinical examination, a high index of suspicion and rapid enzyme testing are the keys to catching it early. For paediatricians, paediatric neurologists and metabolic teams.
This case-based session focuses on the early diagnosis of metachromatic leukodystrophy (MLD) in children � the phase when the condition is most treatable but hardest to recognise. Dr Simon Jones reviews the disease spectrum, from the severe late-infantile form (around half of children, presenting at roughly two to two and a half years with no residual enzyme activity and rapid progression) to the more slowly progressive juvenile and adult forms, and explains why the earliest features are subtle and non-specific. The first case is a boy whose in-toeing and suspected flat feet at 20 months were assessed remotely during the COVID-19 pandemic and attributed to a minor orthopaedic problem. Only when he was finally examined face-to-face were increased muscle tone, a wide-based gait and a plateau in speech recognised, prompting an MRI that showed widespread white-matter abnormality and, on enzyme testing, a diagnosis of late-infantile MLD. Confusingly, his reflexes were absent rather than brisk � because MLD combines a central leukodystrophy with a peripheral neuropathy. The second case is a seven-year-old girl whose speech, motor and behavioural difficulties were initially labelled dyspraxia, dyslexia and developmental coordination disorder; progressive decline, dystonic movements and a more subtle MRI eventually led to a diagnosis of early-juvenile MLD. Dr Jones draws out the practical lessons: maintain a high index of suspicion when a young child shows new, hard neurological signs; remember that progression over time � problems getting worse and new problems emerging � is the key discriminator from static conditions such as simple dyspraxia; and prioritise the rapidly progressive, treatable leukodystrophies, especially MLD and X-linked adrenoleukodystrophy, using very-long-chain fatty acids and a lysosomal enzyme screen (with arylsulfatase A) sent urgently. He emphasises that clinical examination is often more enlightening than any panel of tests, and that early diagnosis is critical because treatment options depend on catching the disease with the fewest possible neurological signs. A Q&A on misdiagnosis, ADHD, laboratory testing and visual and speech involvement follows.
After viewing this webinar, participants will be able to:
Presentation depends on age of onset. Late-infantile MLD, the commonest and most severe form, usually appears at around two to two and a half years with motor problems � in-toeing, an unsteady or wide-based gait, increased muscle tone and frequent falls � after normal early development. Early-juvenile MLD tends to present later with a mix of motor difficulties and cognitive or behavioural change, such as declining school performance and clumsiness. Because MLD also affects the peripheral nerves, reflexes may be absent rather than brisk, which can be confusing.
Because the first features are subtle and mimic far commoner childhood problems. In Dr Jones's cases, early signs were attributed to flat feet and in-toeing, then to dyspraxia, dyslexia and developmental coordination disorder. Juvenile-onset children are frequently labelled with ADHD or learning difficulties. The distinguishing feature is progression: unlike static conditions, MLD gets worse over time and new neurological problems emerge, so a child who is deteriorating or who has hard neurological signs on examination needs urgent investigation.
The fastest route is usually an enzyme level (arylsulfatase A) measured in leukocytes, often as part of a white-cell lysosomal enzyme screen on a blood sample; urinary sulfatide excretion is raised and can support the diagnosis. Because MLD and X-linked adrenoleukodystrophy are both rapidly progressive and treatable, very-long-chain fatty acids should be sent alongside the enzyme screen. Genetic testing (ARSA sequencing, or a rapid leukodystrophy panel where available) confirms the diagnosis, but panels can take months, so biochemistry is often quicker. Dr Jones advises not relying on any single test and speaking to the local metabolic laboratory to get the fastest result.
ADHD and developmental delay are far commoner than MLD, so most children with them do not need metabolic testing. Suspicion should rise when there is 'something extra' � attention or learning problems accompanied by motor concerns or actual neurological signs, or a delay that is accompanied by regression. The key is review over time: MLD does not improve, it progresses, and new problems appear. Careful history-taking and simple clinical examination are the most reliable way to pick out the child who needs urgent investigation.
This content is intended for healthcare professionals only. The views expressed are those of the presenters and do not necessarily reflect those of Excellence in Pediatrics; their inclusion does not imply endorsement. The content is provided for educational purposes only and does not constitute medical advice or replace independent clinical judgement.