Postmortem Molecular Screening for Cardiac Ryanodine Receptor Type 2 Mutations in Sudden Unexplained Death : R420W Mutated Case With Characteristics of Status Thymico-Lymphaticus

Background Mutations of the cardiac ryanodine receptor type 2 (RyR2) gene are known to cause effort-induced polymorphic ventricular arrhythmia, syncope and sudden death. Methods and Results The possible mutations in the RyR2 gene were examined in 18 autopsy cases of sudden unexplained death (SUD). Two cases were found to have the heterozygous missense mutation in exon 14 (nucleotide change C1258T, coding effect R420W). Both cases showed mild fatty infiltration of the right ventricular apex. Interestingly, 1 case showed an enlarged thymus with accompanying hypertrophy of the tonsils and mesenteric lymph nodes. In addition, a narrowing of the aorta was observed in this case. These phenotypic characteristics are consistent with status thymico-lymphaticus, which combines sudden death with an enlargement of lymphoid organs and hypoplasia of the cardiovascular system. The second case also displayed some characteristics of status thymico-lymphaticus. Conclusion The R420W mutation has already been reported in families with juvenile sudden death and may be causative of sudden death in our cases. Postmortem molecular screening of the RyR2 gene could be useful for investigation for cause of death in SUD. The possible association of the RyR2 mutation with status thymicolymphaticus is discussed.