A small deletion at a specific region on chromosome 15 is associated with a range of neurodevelopmental problems, including developmental delays and seizures, according to a new study published online in this week's Nature Genetics.
Previously, larger deletions that remove 1.5 million base pairs on chromosome 15 were reported in individuals with mental retardation, seizures and schizophrenia. Now, Arthur Beaudet and colleagues report that smaller deletions of about 680,000 base pairs at this region of chromosome 15 were found in ten individuals from four unrelated families that presented with similar neurodevelopmental problems. These smaller deletions remove the entire CHRNA7 gene and part of the OTUD7A gene.
Both OTUD7A and CHRNA7 are genes that are expressed in the brain. CHRNA7 encodes a protein that regulates the flow of ions in neurons; defects in this class of protein have frequently been associated with epilepsy.