Although a large portion of this ethnic group has health care provided by the US Indian health service, little research has been done related to racial consideration in pharmacokinetics or other therapies. In the past, a few studies in the literature which were found to be contradictory were related to metabolism of alcohol. More recently some people investigated traits related to chromosome 4q near a cluster of alcohol dehydrogenase genes. These genes encode enzymes of alcohol metabolism and may be responsible for variants in the ADHIB and ADH4 genes which may protect against the development commonly seen symptoms associated with alcohol dependence in other racial groups. Another is the involving lipoprotein reported that American Indians have a lower prevalence of coronary heart disease related to lower low density lipoprotein cholesterol and higher high density lipoprotein cholesterol levels. There may also be significant ethnic differences in the response to morphine in ventilated patients. They found that despite higher levels of serum M6G levels in Caucasians, native Indians were more susceptible to morphine depression of the ventilator response than Caucasians.