Up to this date, the real cause and major factor for the development of ADHD among children are still unknown. a deeper understanding of this disorder must be extensive in order to see what could be contributory to the development of this disorder. for this reason, many researchers and health care professionals are interested to invest their time and effort in conducting studies which deals with the study of various disorders that affects the young population which include Attention Deficit Hyperactive Disorder (ADHD). Researchers are trying to find out whether the cause of this disorder is something related with heredity and for that matter with the genes that the child is having. Thus, further and extensive researches are conducted to address this inquiry of the possible link between the disorder and the genes of the child.

According to another new study which was published journal Nature Genetics, specific genes found in children with ADHD are involved in signaling pathways which appears to be linked with the said disorder. the Children’s Hospital of Philadelphia researchers said that the findings of the study can pave way for new treatment options which will address the specific genes which signals pathways.

The new study involves the analysis and examination of data gathered from the genes of about 1,000 children who have ADHD. Also, another 4,100 children with no ADHD were included in the study. the findings of the research are then compared and evaluated based on the findings of other researches which involve analysis of a number of children with ADHD.

The researchers conducted series of genome analysis and this revealed that about 10 per cent of the study participants who have ADHD actually had variations in the sequences of the DNA. this means that there are either deletions or duplications in the DNA sequences of the children with ADHD. Specifically, variations were found on the four genes which are part of the glutamate receptor gene family.

Moreover, according to study leader Dr. Hakon Hakonarson, director of the Center for Applied Genomics at Children’s Hospital, he said: “members of the GMR gene family, along with genes they interact with, affect nerve transmission, the formation of neurons, and interconnections in the brain, so the fact that children with ADHD are more likely to have alterations in these genes reinforces previous evidence that the GMR pathway is important in ADHD.”

by oral habits i mean like nail biting and thumbsucking

There is a lot more to ADHD (attention deficit and hyperactivity disorder) than just nail-biting. ADD or ADHD need to be diagnosed by a professional. but yes, there are some instances where oral habits can be an expression of someone with ADHD that's been placed in a stressful situation. (stressful meaning outside their comfort zone).

More common manifestations of oral habits are found in cases of mild Obsessive Compulsive Disorder (OCD).

AD-HD stands for

Attention Deficit Hyperactive Disorder

It basically means the the person would have a short attention span, mood swings, hyper , bad behavior.

Some people may have all of the symptoms and yet some may only have one or two.
I suggest the person go to a doctor.

@ bebotech bad behavior is not a symptom of ADHD