Human geneticist Tayfun Ozcelik discovered homozygosity in a region on chromosome 9p24 in Uner Tan syndrome individuals.[1] The very low density lipoprotein receptor gene (VLDLR) is located in this region, which is involved in the migration of neuroblasts within the brain. Ozcelik found mutations in the VLDRL gene in affected individuals, and suggested that these specific mutations may lead to VLDRL deficiency during the development of the brain.