Study explores genetic factors in neonatal abstinence syndrome

In a prospective multicenter study, investigators found that, among infants with in utero opioid exposure, variants in 2 genes were associated with shorter length of hospital stay and less need for treatment of neonatal abstinence syndrome (NAS).

The study included 86 mother-infant dyads of 36 weeks’ gestational age or older from 5 facilities in Massachusetts and Maine. All the infants had been exposed to maternal methadone or buprenorphine in utero for at least 30 days. Investigators genotyped DNA samples from cord blood, maternal peripheral blood, or saliva for single-nucleotide polymorphisms (SNPs) in 3 genes associated with risk for opioid addiction in adults: µ-opioid receptor (OPRM1), multidrug resistance (ABCB1), and catechol-O-methyltransferase (COMT). They then correlated NAS outcomes with genotype. Investigators also collected demographic information as well as medical diagnoses and results of NAS outcome measures, primarily length of hospital stay, a reflection of overall NAS severity.

Variants in the OPRM1 and COMT genes were associated with a shorter length of hospital stay and less need for NAS treatment. No such significant associations were seen with ABCB1 variants (Wachman EM, et al. JAMA. 2013;309[17]:1821-1827).

COMMENTARY  In one sense, this study confirms what you already know: that every baby is different and that it is difficult to predict how an individual baby is going to handle in utero exposure to a given level of opiates. It is hard to guess which baby will become symptomatic and which will require brief or prolonged withdrawal therapy. The genetic markers identified here may someday help to eliminate some of that unpredictability. I wonder if identification of these genetic variables will eventually translate not only into prognostication, but also to focused individualized therapy. -Michael Burke, MD

DR BURKE, section editor for Journal Club, is chairman of the Department of Pediatrics at Saint Agnes Hospital, Baltimore, Maryland. He is a contributing editor for Contemporary Pediatrics. He has nothing to disclose in regard to affiliations with or financial interests in any organizations that may have an interest in any part of this article.