A new study from the University of California San Francisco indicates that early metabolic profiling of newborns could help identify those at higher risk of Sudden Infant Death Syndrome (SIDS). The research, published in JAMA Pediatrics, suggests that incorporating a broader metabolic test into routine newborn screening may offer a way to pinpoint infants who are more vulnerable to this devastating condition.
SIDS remains the leading cause of sudden, unexplained infant death in the United States, affecting approximately 38.4 per 100,000 live births annually. While certain risk factors like prenatal smoking or alcohol use, low socioeconomic status, prematurity, maternal hypertension, and infant sleeping position have been identified, many SIDS cases lack a clear explanation. Prior research has hinted at a connection between SIDS and undiagnosed metabolic conditions, particularly those related to fatty acid beta-oxidation disorders.
Acylcarnitine Levels Linked to SIDS Risk
To delve deeper into this potential link, Scott Oltman, an epidemiologist at UCSF, and his team conducted a case-control study. They compared 354 SIDS cases with matched controls at a 1:4 ratio. All infants in the study were born between 2005 and 2011 and had undergone standard newborn metabolic screening. The control group was carefully matched to the SIDS cases based on gestational age and birth weight.
The metabolic analysis encompassed the measurement of 12 amino acids, 26 acylcarnitines, free carnitine, two hormones (17-hydroxyprogesterone and thyrotropin), and one enzyme (galactose-1-phosphate uridyltransferase).
The study revealed a significant association between acylcarnitine levels and SIDS risk. Specifically, elevated levels of free carnitine and C-14OH were correlated with an increased risk, while higher levels of C-3, C-5DC, and C-12:1 were associated with a decreased risk.
According to the authors, "Acylcarnitines play a crucial role in transporting fatty acids across the mitochondrial membrane, which is the rate-limiting step in fatty acid β-oxidation. Hence, aberrant levels of acylcarnitines may indicate systemic dysfunction of fatty acid oxidation." They further noted that these findings align with previous studies linking enzymes involved in fatty acid oxidation to SIDS.
Predictive Model Shows Promise
The researchers developed a statistical model incorporating 14 factors, including total parenteral nutrition administration, age at blood spot collection, infant sex, adequacy of prenatal care, race and ethnicity, maternal age, and the measurement of eight metabolites. This model demonstrated a good level of accuracy in predicting SIDS, with an area under the receiver operator curve (AUC) score of 0.70–0.75.
In a test set, the model identified 32 children as having a reasonably high risk of SIDS (probability greater than 0.5), and 20 of these children subsequently died. This group exhibited a 14.4-fold increased risk of SIDS compared to children with a probability of 0.1 or less.
Implications for Targeted Counseling and Therapeutics
"These findings suggest that metabolic profiles at birth may have utility for individualized, targeted counseling aimed at identifying infants with an increased vulnerability to SIDS," the researchers concluded. They also emphasized that these metabolic patterns could provide valuable insights for scientists and clinicians to further investigate the mechanisms of aberrant metabolites in SIDS and develop targeted therapeutics.
