Mitochondrial DNA Point Mutations Detected in Four Cases of The Sudden Infant Death Syndrome

Abstract □ 117

Mutations in the mitochondrial genome (mtDNA) are associated with a number of different diseases and several reports indicates involvement of mtDNA mutations also in the sudden infant death syndrome (SIDS). Studies of the hypervariable D-loop indicates differences in this area between SIDS victims and living controls, and point mutations in families which includes SIDS victims are found in the genes for tRNA^Leu(UUR), ATPase6 and tRNA^Gly. The purpose of the present study was to investigate the part of mtDNA including the tRNA^Leu(UUR) gene and the first part of the ND1 gene (which is a subunit of complex I) in SIDS victims and controls. The subjects consisted of 158 cases of SIDS and 97 controls, and the basepairs in the range of 3230-3320 were investigated using polymerase chain reaction (PCR) and temporal temperature gradient electrophoresis (TTGE). If a mutation were detected this area and the D-loop were sequenced. Three different point mutations (T3290C, T3308C and T3308G) were detected in four of the SIDS cases, while none of the controls were mutated. We also found a high D-loop substitution rate in these four cases. The findings strengthen the theory of involvement of mtDNA mutations in SIDS, and makes it highly interesting to continue both to search for deleterious mutations in mtDNA and to investigate the mothers and other maternal relatives of the SIDS victims.