When an individual has challenges in their learning and behavior, parents and doctors usually want to know why. Now, a consortium of researchers led by Baylor College of Medicine in a report said that the loss of a gene through deletion of genetic material on chromosome 15 is associated with significant abnormalities in learning and behavior. “This research goes about 95 percent of the way to pinning these problems in a specific group of individuals to this gene,” said Dr. Arthur L. Beaudet, chair of molecular and human genetics at BCM. Dr. Beaudet believes that the deletion will be identified in others who experience behavioral problems and schizophrenia, developmental delay and epilepsy. The gene’s role in schizophrenia has been under study for quite some time. In the past, a larger deletion containing more genes had been reported in people with the same combination of disorders. In this research, the colleagues found that a smaller deletion of genetic material was associated with similar problems in 10 members of four families. “This gene encodes a subunit of a nicotinic receptor,” said Beaudet. “It is a gene that mediates the response to nicotine via a receptor whose normal ligand is acetylcholine.” The gene encodes an ion channel protein, which allows ions to flow in and out of neurons in the brain. Previously, when these defects were identified, they were associated with forms of epilepsy or seizure disorder. An international group of researchers in this study identified 10 people from four unrelated families with the same deletion in the chromosome. The area deleted encompasses all of CHRNA7, which encodes a whole subunit of the nicotinic receptor. Nine of the 10 subjects had developmental delay and/or mental retardation, while four of the 10 had seizure disorders or an abnormal electroencephalogram.
