The use of polymorphisms for interleukin IB (IL-1B) exon 5 and interleukin 1 receptor antagonist (IL-1Ra) as markers of susceptibility to febrile seizures was evaluated in Taiwanese children (group 1: 51 with febrile convulsions and group 2: 83 normal controls) at China Medical College Hospital, Taichung, Taiwan. Genotype proportions and allele frequencies in the 2 groups were not significantly different for IL-1B exon 5, but were significantly different for IL-1Ra. Frequencies of alleles I and II for IL-1Ra were 100 (98%) and 2 (2%) in group 1 and 152 (91.6%) and 14 (8.4%) in group 2. The IL-1Ra allele I is associated with a higher susceptibility to febrile convulsions. 
COMMENT. Interleukin 1 receptor antagonist may be a useful marker for predicting susceptibility to febrile convulsions. In an editorial, Lewis DB of Stanford University comments that interleukin 1 was one of the first cytokines discovered and is an endogenous pyrogen . Febrile seizures may be added to the list of diseases associated with IL-1Ra polymorphisms. The frequency of IL1RN allele 2 is decreased in Taiwanese children with febrile convulsions compared with controls. However, the frequency of allele 2 in the case controls was lower than that reported in US and European studies. The finding should be confirmed in other populations.
Febrile convulsions and SIDS showed no shared susceptibility in a study of siblings of children with a history of febrile convulsions compared to siblings of children who never had a febrile convulsion. The rate of SIDS was 1.64/1000 person years in the two cohorts. There was no increased risk of SIDS in siblings of children hospitalized with a febrile convulsion . A possible etiological relation between SIDS and febrile convulsions was suggested by Sunderland R, Emery J . Hyperthermia is reported to be common in SIDS.