INCREASED NUMBER OF SUBSTITUTIONS IN THE D-LOOP OF MITOCHONDRIAL-DNA IN THE SUDDEN-INFANT-DEATH-SYNDROME

The purpose of the present study was to investigate substitutions in t he D-loop of mitochondrial DNA (mtDNA) in sudden infant death syndrome (SIDS) and controls, since several observations indicate the involvem ent of mtDNA mutations in SIDS. These include elevated levels of vitre ous humour hypoxanthine in SIDS victims, familial clustering without m endelian traits, and observations of increased sleepiness and a lower activity score in infants who later succumbed to SIDS. Eighty-two case s of SIDS and 133 controls were investigated and the D-loop sequences were recorded in the base-pair range 16 055-16 500 in the mtDNA sequen ce. The sequencing was carried out using the Applied Biosystems Sequen ase dye terminator method and a ABD373A sequencer. The recorded D-loop sequences were compared with the Cambridge sequence and differences w ere recorded as substitutions. The SIDS cases had a tendency towards a higher substitution rate in the D-loop than the controls (p = 0.088). This observation makes it interesting to search for deleterious mutat ions in other locations in the mtDNA.