Delineation of the cognitive phenotype of KBG syndrome

Abstract

Objective: KBG syndrome is caused by a mutation in the ANKRD11 gene and characterized by a short stature and specific dental, craniofacial and skeletal anomalies. The relatively limited amount of literature on phenotypical presentation, mentions delayed speech and motor development as well as mild to moderate intellectual disabilities. As to psychopathology, autism and ADHD are often described, but not yet substantiated in terms of neurocognitive variables. Aim of the current study was to investigate neurocognitive aspects of KBG syndrome, in particular attentional and social cognitive functioning. Participants and Methods: Seventeen patients (aged 6-66 years; ten females) with an ANKRD11 mutation were compared with two different groups of patients with genetic disorders and similar mental ages (n=14 and n=10). Neuropsychological assessment was performed focusing on the level of intellectual functioning and on attention, memory, executive functioning, and social cognition). Results: Preliminary results showed mild to moderate intellectual disabilities (TIQ 45-84, M=63.5, SD=10.7). Mean mental age (M=6.4 years, SD=2.6 years) was lower than mean chronological age (M=11 years, SD=5.7 years). When compared to both control groups, results indicated a relatively strong processing speed and social cognitive functioning and a relatively weak performance on the direct recall of auditory memory tasks. Conclusions: The cognitive profile of this group of 17 patients with KBG is characterized by mild intellectual disability and diminished sustained attention in verbal tasks that fits the ADHD symptoms descripted in the scarce literature on KBG. Implications for diagnostic procedures and clinical management the syndrome are discussed.