Objective: To study the association of dopamine beta-hydroxylase gene 5' flanking region polymorphism-1021 C-->T with attention deficit hyperactivity disorder (ADHD) in Han children.
Methods: ADHD was diagnosed according to the DSM-IV criteria. DNA was extracted and PCR was performed to examine the DBH-1021C-->T polymorphism. HHRR was used to test the association of dopamine beta-hydroxylase gene with different subtypes of ADHD.
Results: HHRR results showed this polymorphism had a tendency to be associated with the inattention subtype (P=0.067) and the combined subtype (P=0.076). The T allele was the protective factor of the inattentive subtype (P=0.07), and the risk factor of the combined subtype (P=0.08). After dividing the 292 nuclear families according to sex, DBH-1021C-->T polymorphism was found to be associated with the combined subtype (P=0.04) with the T allele as the risk factor (P=0.02). There were no positive findings among the girl nuclear families of ADHD.
Conclusion: DBH gene is related to ADHD combined subtype and inattention subtype. The genetic basis of ADHD combined subtype and is inattention is different, and is influenced by sex factor.