KBG syndrome and the establishment of its neuropsychological phenotype

Abstract

Objective: KBG syndrome is caused by a mutation in the ANKRD11 gene, characterized by short stature and specific dental, craniofacial and skeletal anomalies. Scarce literature on the phenotypical presentation mention delayed speech and motor development as well as mild to moderate intellectual disabilities. As to psychopathology, often, autism and ADHD are mentioned but not yet substantiated in terms of neurocognitive variables. Aim: Aim of the current study was to investigate neurocognitive aspects of KBG syndrome. Participants and Methods: Seventeen patients (aged 6–66 years; ten females) with a proven ANKRD11 mutation were compared with two different groups of patients with a genetic disorder and similar developmental 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: In KBG patients, mild to moderate intellectual disabilities (WAIS IV Total IQ = 63.5 ± 10.7, range: 45-84) were established with a mental age that was lower than mean chronological age (6.4 ± 2.6 years versus 11 ± 5.7 years, respectively). When compared to both control groups, results indicated a relatively strong processing speed and social cognitive functioning of patients with KBG while direct recall of auditory memory was relatively poor most probably due to attentional dysfunction. 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. Implications for diagnostic procedures and clinical management of the syndrome are discussed, also with regard to the question how this relates to classificatory diagnosis of ADHD.