There are many causes of sudden infant death syndrome — many of which are unknown. However one possible cause is a link between Medium-chain acyl-coenzyme A dehydrogenase deficiency and sudden infant death syndrome
“Medium-chain acyl-coenzyme A dehydrogenase (MCAD) is one of the enzymes involved in mitochondrial fatty acid β-oxidation, which fuels hepatic ketogenesis, a major source of energy once hepatic glycogen stores become depleted during prolonged fasting and periods of higher energy demands.”
Wikipedia says about MCAD deficiency…
“Prior to expanded newborn screening, MCADD was an underdiagnosed cause of sudden death in infants. For individuals who have been identified prior to the onset of symptoms have an excellent prognosis.”
Kevin Ahern’s biochemistry lecture mentions this link as well.
There is other theory that says …
“defective signaling of serotonin in the brain may be the root cause of sudden infant death syndrome (SIDS).” [wikipedia]