A large de novo distal 16p11.2 deletion in a patient with normal intelligence: Evidence for a neuropsychological phenotype

Objective: The 16p11.2 microdeletion syndrome is characterized by a wide range of phenotypic expressions and is often associated with developmental delay, symptoms from the autism spectrum, epilepsy, congenital anomalies and obesity. Usually, these phenotypes are related to a proximal 16p11.2 deletion of ~600 kb (BP4-BP5) that includes the SH2B1 gene which is reported to be causative for morbid obesity. This more centromeric deletion, however, is functionally different from the more distal 16p12.2p11.2 region which includes the so-called atypical 16p11.2 BP2-BP3 deletion presenting with developmental delay, 26 behavioural problems and mild facial dysmorphisms. The current study aims at the cognitive phenotyping of this novel distal deletion. Participants and Methods: An adult male with a long history of maladaptive behaviours was referred for diagnostic assessment of his a-motivational features. Assessment comprised Kaufman Adult Intelligence Test (KAIT), Cambridge Neuropsychological Test Automated Battery (CANTAB), Autism Diagnostic Observation Schedule (ADOS), and Minnesota Multiphasic Personality Inventory (MMPI-2-RF). Results: Extensive neuropsychological examination demonstrated rigid thinking, anxious beliefs and ideas of reference in the presence of normal intelligence. Microarray analysis demonstrated a de novo 970 kb 16p11.2 BP1-BP4 microdeletion that can be regarded as explanatory for his behavioural profile. Conclusions: The distal 16p11.2 deletion phenotype is not exclusively related to developmental delay nor to autism spectrum disorders. Rather, it has a highly variable presentation that may include, as demonstrated in the present neuropsychological profile of the present patient, high average intelligence and social cognitive dysfunctions referring to Asperger’s syndrome. It is concluded that genetic testing may be of putative relevance for the understanding of neuropsychiatric and neuropsychological phenomena