Abstracts

Rationale: Chromosome 15q duplication syndrome (dup15q) is a rare neurogenetic disorder with multiple chromosomal variations. Children with the isodicentric duplication (idic(15)) reportedly have lower cognitive functioning and an increased number of seizures as compared to other forms of dup15q (Conant et al. Epilepsia, 2014). We sought to examine whether a presence or absence of seizures was related to differing neuropsychological profiles of children with idic(15).Methods: Twenty children with idic(15) (Mean age=7.87, SD=4.39) were evaluated as part of their standard clinical care at Massachusetts General Hospital. Eleven of these children had no seizures or mild, non-Lennox-Gastaut type seizures (–SZR), and 9 children had spasms, tonic, or atonic type seizures (+SZR). Adaptive behavior was examined through parent report on the Vineland Adaptive Behavior Scales – 2nd ed. (VABS-II). Receptive language was evaluated by children’s performance on age-appropriate neuropsychological measures. Data were analyzed using Independent Samples t-Tests.Results: A significant difference between groups was found in overall motor abilities. The +SZR group scored worse on the VABS-II motor composite measure (p=0.046); however, both groups scored well below normative level (Mean=55.95, SD=9.98). A significant difference between groups’ fine motor skills was found, with the +SZR group performing worse than the –SZR group (p=0.049). Gross motor skills approached significance at p=0.057, with the +SZR group exhibiting fewer gross motor abilities. No significant difference between groups was found on VABS-II scores of adaptive behavior. No significant differences between groups were found on measures of receptive language; though both were well below the mean (Mean=63.08, SD=13.79).Conclusions: Both groups performed well below average, suggesting that aggressive and appropriately targeted early interventions will be crucial to support the development of adaptive behaviors and receptive language skills in children with the idic(15) variation. While both of these groups will require early intervention to make developmental gains, it is important to continue to follow these children since differences may emerge as cognitive and adaptive behavior expectations increase with age. The young age of our sample may have contributed to the lack of a significant difference in adaptive functioning between the groups. Additionally, as there was no difference between groups’ receptive language scores, substantial early language intervention will be necessary for children with the idic(15) variation. Furthermore, because motor skills were significantly more delayed in children with seizures as compared to those without, they should receive additional and more intensive occupational therapy. Based on our findings, it’s possible that the presence of the idic(15) duplication has such a profound effect on cognitive and adaptive functioning that the effect of seizures is not apparent on the administered measures; additional research is needed to investigate this further.