Is SIDS a genetic disease?
Some researchers claim that there are certain mutations in human genome that are responsible for elevated risk of sudden infant death syndrome. For example, in Japan almost 10% of SIDS cases are associated with certain mutations of cardiac ion channels (Otagiri et al, 2009):
Sudden infant death syndrome (SIDS) is multifactorial and may result from the interaction of a number of environmental, genetic, and developmental factors. We studied three major genes causing long QT syndrome in 42 Japanese SIDS victims and found five mutations, KCNQ1-K598R, KCNH2-T895M, SCN5A-F532C, SCN5A-G1084S, and SCN5A-F1705S, in four cases; one case had both KCNH2-T895M and SCN5A-G1084S. (…) Our data suggests that nearly 10% of SIDS victims in Japan have mutations of the cardiac ion channel genes similar to in other countries.
However latest exome sequencing indicates that mutations in ion channels that were supposed to correlate with myocardiopathy-related SIDS incidences (Brion et al, 2009) are much more common than they were thought (Andreasen et al, 2013). In other words, observed genetic associations seem to be only a result of small size sampled.
Also, prevalence of SIDS should be higher in twins if one of children had SIDS incidence. However, recent work by Platt and Pharoah found no evidence that:
In spite of a lower risk of SIDS in twins compared with singletons for each birth weight group <3000 g, one component of the higher crude relative risk of SIDS in twins is attributable to the higher proportion of twins that are of low birth weight. A second component is the higher risk in twins compared with singletons for those of birth weight ≥3000 g. Like sex are at no greater risk than unlike sex twins, which suggests that zygosity is not a significant factor in SIDS.
So, genetics does not seem to be a factor in SIDS. Current analyses do not confirm a link between mutations in human genome and higher risk of sudden infant death syndrome.
SIDS and race
On the other hand, there is a clear correlation between race and frequency of sudden infant death incidences. The frequency (per 100,000 live births) of infant deaths range from 20.3 for Asian/Pacific Islander to 119.2 for American Indians/Alaska Native. African American infants have a 24% greater risk of having a SIDS related death than Caucasian infants. However, this could be explained by cultural factors as more than 50% of African American infants were placed on their tummy for sleeping – the position that is absolutely not recommended and has been linked to SIDS.