Novel Variants in the CLCN1, RYR2, and DCTN1 Found in Elderly Japanese Dementia Patients: A Case Series

Identification of Mutations of the RYR2 in Sudden Infant Death Syndrome

BACKGROUND

Despite efforts by the National Education on Sleeping Environment to reduce sudden infant death syndrome (SIDS), it remains the leading cause of post-neonatal mortality. In Korea, the incidence of SIDS was estimated at 0.4 per 1,000 infants in 2022. Mutations in the ryanodine receptor 2 (RYR2) gene, known to be associated with catecholaminergic polymorphic ventricular tachycardia, have been implicated in cases of sudden death. However, genetic studies investigating the link between RYR2 mutations and SIDS have not been conducted in Korea.

METHODS

We extracted DNA from archived formalin-fixed, paraffin-embedded myocardial tissues from 249 SIDS cases autopsied between 2005 and 2017. DNA analysis focused on sequencing key exons (3, 8, 14, 15, 37, 42, 44-47, 49, 50, 83, 87-91, 93-95, 97, 99, and 100-105) of the RYR2 gene, critical for its functional role.

RESULTS

Among the 249 SIDS cases, 62% were male infants, with an average age of 124 days, all of Asian-Korean descent. We identified two previously unreported RYR2 variants in two Korean patients with SIDS, namely c.13175A>G (p.Lys4392Arg) and c.4652A>G (p.Asn1551Ser).

CONCLUSION

Our study identified two RYR2 variants (c.13175A>G/p.Lys4392Arg and c.4652A>G/p.Asn1551Ser) associated with SIDS through postmortem genetic analysis. Given the limited diagnostic yield, our findings underscore the importance of selectively performing molecular autopsies in cases with documented familial clinical history. This approach aims to enhance the quality of genetic counseling available to affected families.