Genetic factors of Attention deficit hyperactivity |
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Posted Date: 6/30/2009 |
Blog by: poost |
Viewed: 94
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Category: ADD-ADHD |
ADHD is a psychiatric disorder in which the child is unable to focus, is hyperactive and thereby can’t work properly.
Research in cases of ADHD has shown that there are substantial genetic factors involved in ADHD. It is a disorder that is familial and heritable in distribution and the genetic susceptibility is seen in 60% to 80% of cases. The families of ADHD children are known to have a much higher incidence of this disease as compared to families of non ADHD children .Boys are 4 to 9 times more prone to ADHD according to a study carried out at Washington School of medicine. A study carried out regarding twins has also proven the fact that genetics play the most important role in the etiology of ADHD. In identical twins there was 80% susceptibility if one is suffering from ADHD as compared to non identical twins in which it is 50%.
There is no single gene yet identified by the study of molecular genetics which can be held responsible for ADHD however a number of candidate genes have been identified. Some of the research has focused upon the role of dopamine receptor genes like DA D2, DA D4 and DA D5 genes but the most important gene recognized in this regard is the seven repeat allele of DR D4 which mediates an intracellular response to DA and DA T1 related with an elevated reuptake of dopamine back into the neuron.
Variations in all of the above mentioned genes have been identified in cases of ADHD. These genes have been associated with novelty seeking and extroversion. According to the opinion of experts the genetic variants may have appeared thousands of years ago and may have affected half of the children suffering from ADHD. They are also believed to benefit their early carriers. IN such people the genetic predilection for novelty seeking might have enhanced their potential in reproduction, mating, hunting and achieving dominance.
Another very important genetic factor is the genetic resistance to thyroid hormone. The individuals suffering from this disorder have a relatively severe form of ADHD. It is not a very important cause of ADHD but still children having familial thyroid diseases have more chances of suffering from ADHD and are considered to be the high risk ones. All these factors indicate in a clear cut way that ADHD is a heritable and familial neurological disorder.
The establishment of the role of genetics in ADHD and the identification of the responsible genes is very significant as it can help in sorting out the treatment strategy for high risk individuals. The high risk individuals include those who have someone suffering in his family with ADHD. Boys are at high risk than girls. If someone among the first degree relatives suffers from ADHD the risk is far greater as compared to second degree relatives. Also the role of thyroid hormone diseases is significant as it is found to be associated with ADHD. So by keeping all these genetic factors in mind the high risk individuals can be spotted and their treatment strategy can be worked out.
But still not one exact gene has been established to be the soul cause of ADHD. Various researches are still being carried on in order to solve the still quite unsolved problem of the etiology of ADHD. If the exact gene is spotted then it will be of great advantage in order to diagnose and treat the disease of ADHD. However, the establishment of the role of dopamine is itself of great help.
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