Mutations affecting the N-terminal domains of SHANK3 point to different pathomechanisms in neurodevelopmental disorders.

Shank proteins are major scaffolds of the postsynaptic density of excitatory synapses. Mutations in SHANK genes are associated with autism and intellectual disability. The effects of missense mutations on Shank3 function, and therefore the pathomechanisms are unclear. Several missense mutations in SHANK3 affect the N-terminal region, consisting of the Shank/ProSAP N-terminal (SPN) domain and a set of Ankyrin (Ank) repeats. Here we identify a novel SHANK3 missense mutation (p.L270M) in the Ankyrin repeats in patients with an ADHD-like phenotype. We functionally analysed this and a series of other mutations, using biochemical and biophysical techniques. We observe two major effects: (1) a loss of binding to δ-catenin (e.g. in the p.L270M variant), and (2) interference with the intramolecular interaction between N-terminal SPN domain and the Ank repeats. This also interferes with binding to the α-subunit of the calcium-/calmodulin dependent kinase II (αCaMKII), and appears to be associated with a more severe neurodevelopmental pathology.

Positive experience with intrathecal baclofen treatment in children with severe cerebral palsy.

INTRODUCTION: Treatment of severe spasticity and dystonia with intrathecal baclofen (ITB) in children has been shown to be effective and has therefore been employed in the Region of Southern Denmark. The aim of this retrospective study was to analyse the efficacy and adverse events since ITB was introduced in 2003. METHODS: A total of 46 children who had a baclofen pump from April 2003 to January 2013 were included. The children's medical records were reviewed and clinical characteristics, efficacy and adverse events were registered. The efficacy of treatment experienced by parents was ascertained by telephone interviews, and data were rated on a Likert scale ranging from one to five, where one was no effect and five was marked improvement. RESULTS: After ITB, spasticity was reduced from a median of four to two in the upper extremities and from a median of four to one in the lower extremities. Baclofen infusion was 105.1-2,000 micrograms/day (mean 494.9 micrograms/day). Oral baclofen was reduced from 27.3 to 17.7 mg/day after ITB (p < 0.01). The parents' assessment of improvement in well-being, function and ease of care of their child had a mean score of 3.7, 2.2 and 3.4, respectively. 87.1% of parents stated that ITB had been worthwhile, and 90.3% would recommend it to other parents. Most infectious and mechanical adverse events were experienced during the first 200 days after pump implantation. The total complication rate was 0.40 per pump year. CONCLUSION: ITB resulted in reduced spasticity in children with severe spasticity and dystonia, and ITB could be considered safe. Parents' satisfaction with ITB was rated as good and most parents would recommend ITB to others. FUNDING: not relevant. TRIAL REGISTRATION: not relevant.