Objectives To determine the characteristics of dopamine D2 receptor gene (DRD2) polymorphisms in drug-exposed and unexposed neonates and the relationship to neonatal abstinence syndrome (NAS).
Design Retrospective case-control analysis between drug-exposed and unexposed infants between DRD2 polymorphisms, drug exposure and NAS treatment.
Patients Drug-exposed (n=48) and drug-free (n=49) infants born between March 1999 and December 2006.
Methods Analysis of DNA for the Taq1A, -141Ins/Del and Ser311Cys DRD2 polymorphisms. Drug exposure was determined by antenatal maternal drug and alcohol history. Frequency measures of DRD2 polymorphisms were compared between drug-exposed infants, treatment NAS medication and with control infants.
Setting Tertiary maternity hospital, Sydney, Australia.
Main outcome measures All infants were born in a good condition (25.7% <37 weeks gestation). Opiates (methadone and heroin) were used by 45 (93.8%) of drug-exposed mothers. The A2A2 allele was more common in drug-exposed infants (37 (77.0%) versus 23 (46.9%), p=0.003) but the A1A2 allele was more common in control infants (23 (46.9%) versus 4 (8.3%), p=0.00002). The-ins allele was more common in control (39 (79.6%) versus 20 (41.7%), p=<0.01) and unmedicated drug-exposed (14/25 (56%) versus 5/23 (21.7%), p=0.02) infants. The majority of infants (41 (83.7%) controls versus 41 (85.4%), p=1.000) expressed the least common, Ser polymorphism.
Conclusions DRD2 polymorphisms are detectable from DNA obtained from stored blood spots. The –ins allele is more common in control and unmedicated drug-exposed infants. Further study is recommended to explore postneonatal outcomes especially in relation to neuropsychiatric behaviours.
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Contributors JLO co-conceived the idea for the project, obtained ethics approval, liaised with the testing centre to obtain blood spots, supervised data analysis and specimen collection, finalised the manuscript and prepared it for publication. MEA-L assisted with the collection of blood spots, provided statistical analysis and drafting and proof-read the manuscript. HXX performed genomic analysis of stored blood spots. KV assisted with statistical analysis and drafting of the manuscript. AA-A assisted with the collection of blood spots and proof-reading of the manuscript. SC assisted with obtaining consents and collection of blood spots as well as proof-reading of the manuscript. JF assisted with obtaining consents and collection of blood spots as well as proof-reading of the manuscript. JF co-conceived the idea for the project, assisted with development of the project design and proof reading of the manuscript. KL assisted with the development of project design and proof reading of the manuscript and supervised blood spot analysis.
Funding This study was supported by the Cornucopia Foundation and the Royal Hospital for Women Foundation and by funding from the Leslie Stevens Fund for Newborn Research, The Cornucopia Foundation and The Royal Hospital for Women Foundation.
Competing interests None.
Patient consent Obtained.
Ethics approval Ethical approval was obtained from South Eastern Sydney Illawarra Health Service.
Provenance and peer review Not commissioned; externally peer reviewed.