Development, behaviour and sensory processing in Marshall-Smith syndrome and Malan syndrome: phenotype comparison in two related syndromes.
Marshall-Smith brings deeper delays than Malan, yet both need sensory-friendly spaces and custom behavior plans.
01Research in Context
What this study did
Doctors compared two rare syndromes that look alike. They tracked growth, learning, and sensory issues in each child.
The team used parent forms and clinic notes to map daily skills and problem behaviors.
What they found
Marshall-Smith children had lower IQ scores and fewer words than Malan children. Both groups hated loud sounds, bright lights, or messy textures.
Each child followed a different path, so one-size plans did not fit all.
How this fits with other research
Tunnicliffe et al. (2011) warned that genes alone do not explain behavior; you must also check what happens right before and after the act. Mulder et al. (2020) now show the same idea in Marshall-Smith and Malan.
van den Broek et al. (2006) found every child with Smith-Magenis had low daily-living scores and lots of stereotypy. The new data line up: both syndromes in the 2020 paper also show wide skill gaps and repetitive habits.
Matson et al. (2008) proved that adult attention keeps problem behavior alive in Smith-Magenis. Mulder et al. (2020) do not test this, but they urge tailored sensory supports, hinting that environment still matters.
Why it matters
When you meet a child with either syndrome, start with a full sensory scan. Note lights, noise, textures. Then pair that data with an ABC check of what triggers and rewards each behavior. Build quiet corners, offer chew tools, and teach replacement communication. These small moves can cut problem minutes and boost learning faster than generic plans.
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02At a glance
03Original abstract
BACKGROUND: Ultrarare Marshall-Smith and Malan syndromes, caused by changes of the gene nuclear factor I X (NFIX), are characterised by intellectual disability (ID) and behavioural problems, although questions remain. Here, development and behaviour are studied and compared in a cross-sectional study, and results are presented with genetic findings. METHODS: Behavioural phenotypes are compared of eight individuals with Marshall-Smith syndrome (three male individuals) and seven with Malan syndrome (four male individuals). Long-term follow-up assessment of cognition and adaptive behaviour was possible in three individuals with Marshall-Smith syndrome. RESULTS: Marshall-Smith syndrome individuals have more severe ID, less adaptive behaviour, more impaired speech and less reciprocal interaction compared with individuals with Malan syndrome. Sensory processing difficulties occur in both syndromes. Follow-up measurement of cognition and adaptive behaviour in Marshall-Smith syndrome shows different individual learning curves over time. CONCLUSIONS: Results show significant between and within syndrome variability. Different NFIX variants underlie distinct clinical phenotypes leading to separate entities. Cognitive, adaptive and sensory impairments are common in both syndromes and increase the risk of challenging behaviour. This study highlights the value of considering behaviour within developmental and environmental context. To improve quality of life, adaptations to environment and treatment are suggested to create a better person-environment fit.
Journal of intellectual disability research : JIDR, 2020 · doi:10.1111/jir.12787