This study identifies a complex chromosomal rearrangement involving chr1 insertion into chr17 as the genetic cause of severe skeletal Class II malocclusion with gingival hyperplasia in a four-generation family, revealing new insights into the role of KCNJ2/KCNJ16 misregulation in craniofacial disorders. This evidence concerns the gene KCNJ2 and gingival disorder.