Copy number variation (CNV) is an important source of genetic differences between individuals and can give raise to observable traits. Certain CNVs are known to cause extreme traits in human and can be the direct cause of a number of severe illnesses. In this project we aim to make use of next generation sequencing datasets across a large UK cohort, to create detailed CNV maps, and to perform robust association testing of copy number variable regions against human phenotypic measurements with a particular focus on brain structure and function.