1p36 Deletion Syndrome is caused by a missing piece (deletion) of chromosome material from the tip of the short arm of chromosome 1. Most people have 46 chromosomes. Chromosomes are arranged in pairs, with one copy coming from the mother and the other from the father. Chromosomes contain the genetic material that our bodies need to grow and develop. People with 1p36 Deletion Syndrome are missing some of the genetic material needed for normal development. Although we do not know exactly why chromosome deletions occur, there is no evidence that parents could have done anything to cause or prevent 1p36 Deletion Syndrome.