Neurofibromatosis type 1 (NF1) is an autosomal dominant genetic condition. While considerable work has focused on cognitive functioning, several research groups also observed difficulties in social functioning as a prominent feature of NF1. These problems and the possible link between NF1 and Autism Spectrum Disorder (ASD) have become increasingly important in recent NF1 literature. The aim of the current study was to assess ASD characteristics in a hospital-based NF1 pediatric population (n = 82) using the standardized Children Social Behavior Questionnaire (CSBQ) and Social Responsiveness Scale (SRS) to account for the prevalence, severity, and nature of social problems. In a parallel study, comprehensive ASD assessment was performed in a subgroup of NF1 children with a strong suspicion of ASD (n = 31). Results indicate that NF1 children have more social problems than typical controls, more frequently reported above 8 years. The SRS shows that 63% is at risk of ASD symptoms. According to item analyses, most problems were observed on items measuring orientation in, understanding of and being tuned onto a social situation (CSBQ) and social cognition and communication (SRS). In the parallel study, 27 NF1 children were diagnosed with ASD. These children have a distinct phenotype compared to a heterogeneous ASD group, with pronounced social-communicative impairments and fewer restrictive/repetitive behaviors. This study provides a better understanding of social problems in NF1 and the phenotypical overlap with ASD symptomatology. Despite their willingness to engage with others, NF1 children with or without ASD encounter various difficulties in their social-communicative life.

Nearly 50% (8/17) of the children showed learning disabilities, when corrected for IQ in the academic evaluations. Isolated impaired literacy skills, particularly spelling problems, were most frequent (4/8), whereas a pure arithmetic learning disability was rare (1/8). Three children presented both learning disabilities. Results on academic and neuropsychological tests did not fit the well-known types of learning disabilities -- nonverbal learning disability (NLD) and dyslexia. Nearly all NF1 children showed visual perceptual and executive dysfunctions. In this study, teachers more frequently reported behavioural problems in NF1 children than parents, as opposed to literature data in a general population. The correspondence of the perception of internalizing problems between the children and teachers was greater than between children and their parents. No correlation was found between the performances on the WISC-R, specific neuropsychological results, academic performances and behavioural problems. The Deficiency in Attention, Motor and Perception (DAMP) concept seems most appropriate in order to describe the neuropsychological deficits and their repercussions on behavioural and academic performances seen in NF1 children.

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