A group of scientists from Baylor College of Medicine claim that the loss of a gene through removal of genetic material on chromosome 15 is associated with considerable abnormalities in learning and behavior.
This study could possibly go about 95 percent of the way to joining these problems in a specific group of individuals to this gene. According to Arthur Beaudet, the deletion will perhaps be recognized in other people with behavioral problems along with schizophrenia, developmental delay and epilepsy. Apparently, the gene’s role in schizophrenia has been in study for a while.
Earlier, a larger deletion containing more genes seems to have been reported in people with the same collection of disorders. In this study, Beaudet, Dr. Pawel Stankiewicz and colleagues found that a smaller deletion of genetic material i.e. the entire gene in question, CHRNA7, and a part of another may be associated with similar problems in 10 members of four families.
“We scanned the genome of about 10,000 people to find this rare but important defect,” says Dr. Pawel Stankiewicz assistant professor of molecular and human genetics at BCM.
Dr. Arthur L. Beaudet, chair of molecular and human genetics at BCM said that, “This gene encodes a subunit of a nicotinic receptor. It is a gene that mediates the response to nicotine via a receptor whose normal ligand is acetylcholine.”
The gene is known to encode a protein called an ion channel which allows ions to flow in and out of neurons in the brain. Supposedly, defects in ion channels have earlier been related to forms of epilepsy or seizure disorder.
“If insufficient expression of the nicotinic receptor causes most or all of the problems associated with deletions in this particular area of chromosome 15, then it offers a target for drug treatment,” says Stankiewicz.
One such drug mentioned in the study appears to be Chantix, a medicine now used in efforts to stop smoking. In this study, an international group of scientists were observed to have recognized 10 people from four unrelated families with the same deletion in the chromosome. The area deleted is known to include all of CHRNA7, which encodes a whole subunit of the nicotinic receptor.
The findings revealed that nine of the 10 subjects seemed to have developmental delay and/or mental retardation. Moreover, four of the 10 appeared to have seizure disorders or an abnormal electroencephalogram (EEG).
In two of the families studied, the patients were noted to have inherited the deletion from a parent. In addition, in one family, the authors found the same deletion in the patient’s mother, two siblings, maternal aunt and maternal grandmother. Further, both the patient’s mother and her sister seemed to have mental retardation and epilepsy.
His both siblings may perhaps have developmental delay. Besides, the patient was noted to have severe mental retardation and obesity and mild facial dysmorphism. It was observed that a second patient with impaired growth and severe developmental delay inherited her deletion from her mother, who had normal intelligence but had suffered from epilepsy from childhood.
The findings of the study have been published in the journal, Nature Genetics.