PURPOSE: Sudden infant death syndrome (SIDS) is the commonest cause of sudden death of an infant; however, the genetic basis remains poorly understood. We aimed to identify noncardiac genes underpinning SIDS and determine their prevalence compared with ethnically matched controls.
METHODS: Using exome sequencing we assessed the yield of ultrarare nonsynonymous variants (minor allele frequency [MAF] ≤0.00005, dominant model; MAF ≤0.01, recessive model) in 278 European SIDS cases (62% male; average age =2.7 ± 2 months) versus 973 European controls across 61 noncardiac SIDS-susceptibility genes. The variants were classified according to American College of Medical Genetics and Genomics criteria. Case-control, gene-collapsing analysis was performed in eight candidate biological pathways previously implicated in SIDS pathogenesis.
RESULTS: Overall 43/278 SIDS cases harbored an ultrarare single-nucleotide variant compared with 114/973 controls (15.5 vs. 11.7%, p=0.10). Only 2/61 noncardiac genes were significantly overrepresented in cases compared with controls (ECE1, 3/278 [1%] vs. 1/973 [0.1%] p=0.036; SLC6A4, 2/278 [0.7%] vs. 1/973 [0.1%] p=0.049). There was no difference in yield of pathogenic or likely pathogenic variants between cases and controls (1/278 [0.36%] vs. 4/973 [0.41%]; p=1.0). Gene-collapsing analysis did not identify any specific biological pathways to be significantly associated with SIDS.
CONCLUSIONS: A monogenic basis for SIDS amongst the previously implicated noncardiac genes and their encoded biological pathways is negligible.