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Autism spectrum disorder in a child with megalencephaly-capillary malformation-polymicrogyria syndrome (MCAP)
  1. Lily JE St John1 and
  2. Naveen Rao2
  1. 1School of Medical Sciences, University of Manchester, Manchester University NHS Foundation Trust, Manchester, Greater Manchester, UK
  2. 2Paediatrics Wythenshawe, Manchester University NHS Foundation Trust, Manchester, Greater Manchester, UK
  1. Correspondence to Lily JE St John; lilystjohn98{at}


Megalencephaly-capillary malformation-polymicrogyria syndrome (MCAP) is a rare disorder that arises as a result of a somatic mosaic mutation in the PIK3CA gene. It characteristically presents with postnatal or congenital megalencephaly, cutaneous capillary malformations, postaxial polydactyly and often segmental or focal body overgrowth. We report a 7-year-old boy with known MCAP who was diagnosed at around 10 months old with a mosaic change in the PIK3CA gene. He was found to have hall-mark clinical signs; macrocephaly and four-limb postaxial polydactyly. Since diagnosis, he has had multiple clinical features, most of which typically present in children with MCAP. He has now been diagnosed with autism spectrum disorder (ASD), demand avoidance and is under assessment for attention deficit hyperactivity disorder. Although some cases have been raised to the M-CM Network, to our knowledge this is the first case of ASD in MCAP to be reported in the literature.

  • sleep disorders (neurology)
  • paediatrics
  • developmental paediatrics

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  • Contributors LSTJ provided the idea of the article, gained the consent and was responsible for writing the report. NR was responsible for editing and making revisions to the article, as well as being the clinician responsible for the patient.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Case reports provide a valuable learning resource for the scientific community and can indicate areas of interest for future research. They should not be used in isolation to guide treatment choices or public health policy.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.