Polymorphic admixture typing in human ethnic populations.

A panel of 257 RFLP loci was selected on the basis of high heterozygosity in Caucasian DNA surveys and equivalent spacing throughout the human genome. Probes from each locus were used in a Southern blot survey of allele frequency distribution for four human ethnic groups: Caucasian, African American, Asian (Chinese), and American Indian (Cheyenne). Nearly all RFLP loci were polymorphic in each group, albeit with a broad range of differing allele frequencies (delta). The distribution of frequency differences (delta values) was used for three purposes: (1) to provide estimates for genetic distance (differentiation) among these ethnic groups, (2) to revisit with a large data set the proportion of human genetic variation attributable to differentiation within ethnic groups, and (3) to identify loci with high delta values between recently admixed populations of use in mapping by admixture linkage disequilibrium (MALD). Although most markers display significant allele frequency differences between ethnic groups, the overall genetic distances between ethnic groups were small (.066-.098), and < 10% of the measured overall molecular genetic diversity in these human samples can be attributed to "racial" differentiation. The median delta values for pairwise comparisons between groups fell between .15 and .20, permitting identification of highly informative RFLP loci for MALD disease association studies.

Alcoholism and substance abuse among selected southern Cheyenne Indians.

This family and small community-based study reports the occurrence of alcoholism and co-occurring substance abuse in Southern Cheyenne Indians living in western Oklahoma. Sociocultural factors complicate operationalization of clinical data into standard (DSM-III-R) psychiatric disorder terminology; understanding sociocultural factors is essential for assessing the high rate of addictive disorders in this group. To obtain reliable and valid clinical diagnoses, data from several sources were utilized within a blind rating system: 1) SADS-L, a clinician-administered research diagnostic instrument; 2) MAST; 3) relatives; 4) medical records; 5) other official documents. The sample consisted of 69 males (45 alcoholics) and 97 females (36 alcoholics). Among clinically significant substance abusers (moderate impairment of function), 22 of 24 were alcoholics. In non-alcoholics, mean MAST scores were 8.8 (males) and 5.1 (females); in alcoholics, 32.0 (males) and 38.7 (females). Mean age of onset on heavy use of alcohol was 20.1 yrs. (males) and 22.8 (females) (p = 0.047); among all alcoholics, 86% (males) and 64% (females) had early onset (< 25 yrs. old). When data from 98 unrelated subjects were analyzed separately, similar findings were observed except that mean age of onset of heavy use of alcohol was more discrepant between males and females, viz. 20.1 versus 22.8 yrs. (p = 0.02). Among those with substance abuse disorders, early age of onset was present in all but one female. In these Cheyenne, alcoholism is usually clinically severe and early in onset; it often co-occurs with substance abuse, also early in onset.