 This has led to several conditions that involve this region being identified, including TAR syndrome and the more general classifications of 1q21.1 deletion syndrome and 1q21.1 duplication syndrome.Studies of deletions and duplications in the 1q21.1 region have consistently revealed microcephaly in association with deletions and macrocephaly in association with duplications.Genome sequences indicate that the Olduvai protein domain first appears as part of the myomegalin gene ("PDE4DIP") on chromosome 1q36 in mammals at least 200 million years ago.