Association Between DRD4 rs747302 and VNTR Polymorphisms and Drug Addiction in An Iraqi Population

Drug addiction is a neuropsychiatric disorder characterised by compulsive drug-seeking behaviour notwithstanding adverse consequences. This work seeks to address a deficiency in the literature by comparing drug-addicted and non-addicted individuals within an Iraqi population through the analysis of a 1000-base pair variable number of tandem repeats (VNTRs) polymorphism of the dopamine receptor gene DRD4. The association of this novel polymorphism with drug addiction has not yet been examined.

A total of 270 people were registered between May 2022 and June 2023. Of these, 180 had drug addictions and 90 were healthy controls. DNA was extracted from the participants' blood samples. Restriction Fragment Length Polymorphism was used to investigate genetic polymorphisms in the DRD4 and VNTR genes to identify differences.

The genotype frequencies differed markedly between the control group (GC, 3% frequency) and the patient group (GC, 37% frequency). The control group had more of the genotype that was more common among addicts. The C allele was present in 60% of the patients but in only 1% of the controls. The results showed that the CC genotype is more common in the patient group than in the control group. A comparison of repetitions between the control and patient groups was made based on the distribution of genotypes of SNP rs747302. Patients with the GG genotype had an average of 17 repetitions, whereas those with the GC genotype had 18, and those with the CC genotype had 18.3. The results showed that people in the CC genotype group had a lot more repetitions.

The results of our study indicated that the CC, GC, and VNTR genotypes significantly contribute to heroin addiction risk in Iraqis.