Genetic counseling for susceptibility loci and neurodevelopmental disorders: the del15q11.2 as an example

In recent years, several recurrent copy number variations (CNVs) that confer risk of neurodevelopmental disorders have been identified (e.g., del and dup 16p11.2, del15q13.3, del and dup 1q21.1, del16p13.3, del15q11.2). They are often inherited from an unaffected parent and lack phenotypic specificity. Although there is growing evidence from association studies to consider them as susceptibility CNVs, their clinical utility is debated. Yet the clinician is frequently challenged to deal with these counseling situations without guidelines or consensus. In this report, counseling issues and research opportunities are discussed, with the recurrent 15q11.2 BP1-BP2 (including CYFIP1, NIPA1, NIPA2, TUBGCP5) as an example. Several clinical reports have been published describing patients with del15q11.2 featuring intellectual disability, developmental delay, neurological problems, autism spectrum disorder (ASD), attention problems, speech delay, and dysmorphism. The del15q11.2 was found to be significantly associated with intellectual disability, schizophrenia, epilepsy, and ASD. In this report we discuss how patient-specific and family-specific information may alter the interpretation of del15q11.2 as a contributing factor to the disorder in practical counseling situations. In addition, an association study for ASD in a Belgian Flemish cohort and an overview of reported association studies, clinical reports and genomics data for del15q11.2 are presented.