What are the genetic changes related to 22q13.3 deletion syndrome ?
22q13.3 deletion syndrome is caused by a deletion near the end of the long (q) arm of chromosome 22. The signs and symptoms of 22q13.3 deletion syndrome are probably related to the loss of multiple genes in this region. The size of the deletion varies among affected individuals.  A ring chromosome 22 can also cause 22q13.3 deletion syndrome. A ring chromosome is a circular structure that occurs when a chromosome breaks in two places, the tips of the chromosome are lost, and the broken ends fuse together. People with ring chromosome 22 have one copy of this abnormal chromosome in some or all of their cells. Researchers believe that several critical genes near the end of the long (q) arm of chromosome 22 are lost when the ring chromosome 22 forms. If one of the chromosome break points is at position 22q13.3, people with ring chromosome 22 have similar signs and symptoms as those with a simple deletion.  Researchers are working to identify all of the genes that contribute to the features of 22q13.3 deletion syndrome. They have determined that the loss of a particular gene on chromosome 22, SHANK3, is likely to be responsible for many of the syndrome's characteristic signs (such as developmental delay, intellectual disability, and impaired speech). Additional genes in the deleted region probably contribute to the varied features of 22q13.3 deletion syndrome.