title: Polymorphism in variable number of tandem repeats of dopamine d4 gene is a genetic risk factor in attention deficit hyperactive egyptian children: pilot study.
abstract: BACKGROUND
  The variable number of tandem repeats (VNTR) of the dopamine receptor D4 (DRD4) gene among humans may elucidate individual differences in susceptibility to neuropsychiatric diseases. Dopamine dysfunction may be involved with Attention Deficit Hyperactivity Disorder (ADHD) symptoms. In this study, we report the association between the phenotype of ADHD, a condition characterized by inattentiveness, hyperactivity, and impulsiveness, and a 48-base pair VNTR in exon 3 of the DRD4 polymorphism.
  
  
  METHODS
  We used a case control approach conducted on 29 ADHD and 31 ethnically matched control Egyptian children (ages 6-12 years). Cases were assessed by a psychiatric semi-structured interview and the Conners' Parent Rating Scale. VNTR polymorphisms of the DRD4 gene were done by touchdown PCR program using exon 3-specific primers followed by agarose gel electrophoresis.
  
  
  RESULTS
  We observed a significant association between the existence of D4.4 allele of DRD4 and ADHD (P, 0.002); 6.9% of cases showed a single D4.4 and 10.3% showed a double D4.4 as compared to controls in whom D4.4 has never been detected.
  
  
  CONCLUSIONS
  Children with smaller number of repeat alleles (two to four repeats) of the DRD4 gene have higher possibility to develop ADHD in Egyptian children.
authors.affiliation: Professor of Psychiatry, Faculty of Medicine, Cairo University, Egypt.
authors.forename: Ola
authors.initials: O
authors.lastname: Shahin
authors.affiliation: Professor of Human Genetics, National Research Center, Giza, Egypt.
authors.forename: Nagwa A
authors.initials: NA
authors.lastname: Meguid
authors.affiliation: Professor of Psychiatry, Faculty of Medicine, Cairo University, Egypt.
authors.forename: Omnia
authors.initials: O
authors.lastname: Raafat
authors.affiliation: Researcher of Molecular Genetics, Department of Microbial Biotechnology, National Research Center, Giza, Egypt.
authors.forename: Reham M
authors.initials: RM
authors.lastname: Dawood
authors.affiliation: Assistant Researcher of Psychiatry, National Research Center, Giza, Egypt.
authors.forename: Malak
authors.initials: M
authors.lastname: Doss
authors.affiliation: Assistant Professor of Molecular Genetics, Department of Microbial Biotechnology, National Research Center, Giza, Egypt.
authors.forename: Noha G
authors.initials: NG
authors.lastname: Bader El Din
authors.affiliation: Professor of Molecular Genetics, Department of Microbial Biotechnology, National Research Center, Giza, Egypt.
authors.forename: Mostafa K
authors.initials: MK
authors.lastname: El Awady
keywords: ADHD; DRD4; VNTR