Current SIDS research: time to resolve conflicting research hypotheses and collaborate

Genetic Association Study of Acetylcholinesterase (ACHE) and Butyrylcholinesterase (BCHE) Variants in Sudden Infant Death Syndrome (SIDS)

BACKGROUND

Sudden infant death syndrome (SIDS) is the leading cause of death among infants aged between one month and one year. Altered enzyme activities or expression of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) have been observed in SIDS patients that might lead to disturbed autonomic function and, together with other risk factors, might trigger SIDS. To explore the contribution of AChE and BChE from a genomic viewpoint, we sought to investigate the association between SIDS and selected single nucleotide polymorphisms (SNPs) in the ACHE and BCHE genes.

METHODS

In this case-control study, 13 potentially regulatory SNPs were selected from ACHE and BCHE and were genotyped in 201 SIDS cases and 338 controls. The association of SIDS with the 11 successfully genotyped candidate variants was examined using statistical analyses of overall or stratified cases and haplotype analyses.

RESULTS

No significant overall associations were observed between SIDS and ACHE and BCHE variants in allele, genotype, and haplotype analyses. In subgroup analyses, eight variants were found to be nominally associated with SIDS, though these associations did not remain statistically significant after correction for multiple comparisons. One haplotype (T-C-G-C-C in rs3495-rs1803274-rs1355538-rs2048493-rs1126680) of BCHE was associated with the female SIDS subgroup (57.3% in controls vs. 46.3% in female SIDS cases, p = 0.010).

CONCLUSIONS

The selected variants in ACHE and BCHE were not overall associated with SIDS in this study, and thus cannot generally explain the previously reported dysregulation of enzyme activities in SIDS. However, some evidence of association in subgroups and a possible contribution of variants other than those tested here would need to be explored in larger studies.

Rates of Sudden Unexpected Infant Death Before and During the COVID-19 Pandemic

Importance

Infection has been postulated as a driver in the sudden infant death syndrome (SIDS) cascade. Epidemiologic patterns of infection, including respiratory syncytial virus and influenza, were altered during the COVID-19 pandemic. Comparing month-to-month variation in both sudden unexpected infant death (SUID) and SIDS rates before and during the pandemic offers an opportunity to generate and expand existing hypotheses regarding seasonal infections and SUID and SIDS.

Objective

To compare prepandemic and intrapandemic rates of SUID and SIDS, assessing for monthly variation.

Design, Setting, and Participants

This cross-sectional study assessed US mortality data provided by the Centers for Disease Control and Prevention for January 1, 2018, through December 31, 2021. Events with International Statistical Classification of Diseases and Related Health Problems, Tenth Revision codes for SIDS (R95), unknown (R99), and accidental suffocation and strangulation in bed (W75) causes of death were examined. The data analysis was performed between November 2, 2023, and June 2, 2024.

Exposure

COVID-19 pandemic.

Main Outcomes and Measures

The primary and secondary outcomes were the monthly rates of SUID and SIDS during the COVID-19 pandemic (March 1, 2020, to December 31, 2021) compared with the prepandemic period (March 1, 2018, to December 31, 2019) as measured using generalized linear mixed-effects models. Seasonal trends in RSV and influenza rates were also examined.

Results

There were 14 308 SUID cases from January 1, 2018, to December 31, 2021 (42% female infants). Compared with the prepandemic period, the risk of SUID increased during the intrapandemic period (intensity ratio [IR], 1.06; 95% CI, 1.05-1.07). Monthly assessments revealed an increased risk of SUID beyond the prepandemic baseline starting in July 2020, with a pronounced epidemiologic shift from June to December 2021 (ranging from 10% to 14%). Rates of SIDS were elevated throughout the intrapandemic period compared with the prepandemic baseline, with the greatest increase in July 2021 (IR, 1.18; 95% CI, 1.13-1.22) and August 2021 (IR, 1.17; 95% CI, 1.13-1.22). Seasonal shifts in RSV hospitalizations correlated with monthly changes in SUID observed during 2021.

Conclusions and Relevance

This cross-sectional study found increased rates of both SUID and SIDS during the COVID-19 pandemic, with a significant shift in epidemiology from the prepandemic period noted in June to December 2021. These findings support the hypothesis that off-season resurgences in endemic infectious pathogens may be associated with SUID rates, with RSV rates in the US closely approximating this shift. Further investigation into the role of infection in SUID and SIDS is needed.

Sudden Infant Death Associated with Rhinovirus Infection

A less than one-month-old infant with symptoms of rhinitis died unexpectedly in his sleep. He was not born prematurely and had no known underlying disease. Cerebrospinal fluid, nasopharyngeal and lung samples, and rectal swab were found to be positive for subgroup A rhinovirus, while the blood was negative. This case highlights the important finding that the rhinovirus, a common pathogen associated with upper respiratory tract infections, can sometimes, as the only pathogen, lead to complications such as a cerebrospinal infection and be involved in the sudden infant death syndrome (SIDS). Vigilance is necessary in case of viral infections in the infant's environment, and measures of hygiene and protection must be encouraged in order to reduce the risk of the SIDS.