Distribution of interleukin-1 receptor antagonist genotypes in sudden unexpected death in infancy (SUDI); unexplained SUDI have a higher frequency of allele 2.
OBJECTIVE
This investigation was designed to explore the role of IL-1RN genotype in unexplained infant deaths (including sudden infant death syndrome (SIDS)), non-infectious infant deaths, and infectious infant deaths, and to investigate whether IL-1RN genotype is related to the finding of organisms in normally sterile sites in infant deaths.


METHODS
IL-1RN 89bp variable number of tandem repeat polymorphism genotype was determined using polymerase chain reaction for 49 cases of unexplained sudden unexpected death in infancy (uSUDI), 13 cases of infectious sudden unexpected death in infancy, 10 cases of non-infectious sudden unexpected death in infancy, and 103 live control infants. IL-1RN genotype was then compared with the presence of bacteria in normally sterile sites in infant deaths.


RESULTS
An association was found between the homozygous A2 allele and uSUDI (P = 0.007; 95% confidence interval 1.41-17.67) where carriage of the 2/2 genotype was 4.85 times more likely to increase risk of uSUDI compared with the predominant 1/1 genotype.


CONCLUSIONS
The role of infection in uSUDI and SIDS may be via an immune response pathway where IL-1RN A2 affects interleukin (IL)-1 regulation. These results are consistent with previous research where polymorphic genotypes conferring more severe proinflammatory responses are found more frequently in uSUDI/SIDS infants than in controls.
Highet
Amanda R
AR
Department of Microbiology and Infectious Diseases, SA Pathology at the Women's & Children's Hospital, 72 King William Road, North Adelaide, South Australia, Australia. amanda.highet@adelaide.edu.au
Berry
Anne M
AM
Goldwater
Paul N
PN
D001315:Australia; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D053590:Interleukin 1 Receptor Antagonist Protein / Q000235:genetics*; D008297:Male; D011110:Polymorphism, Genetic; D013203:Staphylococcal Infections / Q000150:complications* / Q000276:immunology; D013211:Staphylococcus aureus; D013398:Sudden Infant Death / Q000235:genetics* / Q000276:immunology; D020080:Tandem Repeat Sequences / Q000235:genetics
C507763:IL1RN protein, human; D053590:Interleukin 1 Receptor Antagonist Protein