Microdeletion 3q13.33-3q21.2: A Rare Cause of Neurodevelopmental Disorder

Chromosomal sub-microscopic imbalances, such as microdeletions and microduplications, are associated with multiple genetic disorders. Here, we illustrate microdeletion 3q13.33q21.2 might be responsible for neurodevelopmental disorder in two patients. There are two patients with neurodevelopmental disorder in a family of seven. We used chromosomal microarray analysis to identify the microdeletion 3q13.33q21.2. Next-generation sequencing was utilized to exclude the presence of allelic mutations within the microdeletion region 3q13.33q21.2, which may have a potential role in the development of disease in patients affected with secondary genetic alterations. Patient 4 was diagnosed with dilated left third ventricle, neurodevelopmental disorder, and mild abnormalities in electroencephalogram through a series of clinical examinations. Patient 6 was diagnosed with attention deficit hyperactivity disorder, short stature, intellectual disability, and concurrent epilepsy. By investigating the 3q13.33q21.2 band of the University of California, Santa Cruz database, we screened out the genes related to developmental delay and intellectual disability, including ADCY5 SEMA5B andKPNA1, which were highly suspected to be related to intelligence. This region also involves CASR, a gene that has been reported to be associated with epilepsy. The ADCY5 and SEMA5B genes may be key genes to cause neurodevelopmental disorder. Abnormal expression of the CASR gene may lead to the occurrence of epilepsy.