The phenotype resulting from these large deletions can be readily explained when the deletion disrupts known monogenic disease genes, for example a deletion on chromosome 11p15.1 causes HI, enteropathy and deafness with loss of the ABCC8 gene responsible for the HI and loss of the adjacent gene, USH1C, causing the enteropathy and deafness [8]. The gene discussed is ABCC8; the disease is deafness.