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A polymorphism with a variable number of tandem repeats (VNTR) found in the 3' untranslated region of the human dopamine transporter gene (DAT1) was scored in unrelated individuals drawn from 10 geographically widely dispersed populations in order to assess this marker's usefulness in human population genetics. The populations that were analyzed in this study included 4 indigenous groups of Siberia, natives of North and South America, as well as Caucasian and Oceanic groups, most of which represented small-scale societies. A total of 5 DAT1 alleles were seen overall, but only in one Siberian population, the Altai-Kizhi, were all 5 present, and in the Native Americans of Colombia the locus was monomorphic. The most common allele, DAT1*10, ranged in frequency from 52% in Greeks to 100% in South Americans. The high frequency of the DAT1*10 allele (~90%) among Mongoloid groups of north and east Asia distinguishes them from most Caucasian groups. The presence of the rare DAT1*7 allele in relatively high frequency (~5%) among all Siberian groups suggests a close affinity with north Asian groups, especially Mongolians. The presence of the even rarer DAT1*13 allele in one Siberian population, the Altai-Kizhi, reflects this group's long historical contact with Mongolians. The results demonstrated that the DAT1 VNTR polymorphism is useful in investigating population relationships, and that rare alleles at this locus may be particularly valuable in understanding the extent of genetic affinity between neighboring groups and in situations where admixture is suspected. However, because of both the association and linkage of this VNTR locus with attentiondeficit hyperactivity disorder (ADHD) in children, and its highly restricted polymorphism (usually 3 alleles) in most human groups, the possibility of selection constraints on the DAT1 gene cannot be ignored.

We have screened the mitochondrial genome of 15 men with symptomatic vertebral fractures (median age 62 years, range 27-72 years) and 17 male control subjects (median age 61 years, range 40-73 years) for the presence of mitochondrial DNA (mtDNA) deletions in peripheral monocyte DNA. Polymerase chain reaction analysis provided evidence of a common age-related (4.9 kb) mtDNA deletion situated between nucleotides 8470 and 13.460 of the genomic sequence in 5 of the 17 controls (29%) and 9 of the 15 patients (60%) investigated. Southern blotting and polymerase chain reaction revealed a novel 3.7 kb deletion in 2 patients. One of the affected patients, a 27-year-old man with severe osteoporosis (lumbar spine bone mineral density (BMD) 0.381 g/cm(2); Z-score -6.45) was found to harbor deletion in almost 50% of the mitochondria. The patient had a blood lactic acid level (4.6 nM) that was over 3 times the upper reference range (0-1.3 mM), thus confirming the presence of systemic oxidative stress. Further analysis by modified primer shift polymerase chain reaction showed the 5' breakpoint to be between the nucleotides 10.63 kb and 10.80 kb of the mtDNA. The second patient harboring the 3.7 kb deletion was older (62 years) with less severe osteoporosis (lumbar spine BMD 0.727/cm(2); Z-score -2.58) and the proportion of affected mitochondria was lower (25%). The significance of these findings is discussed and the possible relation between oxidative stress and accelerated bone loss is examined.

In the last 25 years a number of genetic studies on the populations of the Indian subcontinent have been conducted. Unfortunately, most of the studies covered a limited number of genetic systems, and only a few provide information on the genetic differentiation and population structure of some regional caste, tribal, religious, and urban groups. Despite a recent report suggesting that in eastern India genetic affinity does not show any large degree of congruence with sociocultural hierarchy, three distinct surveys reported here indicate that geographic proximity, ethnohistory, and biosocial and cultural affiliation are important determinants of genetic affinity. Gene differentiation studies are few, but from the information of some previous papers and results presented in this special issue of Human Biology, the pattern of differentiation is becoming clear. In general, genetic differentiation in populations of India is low (0.26–1.7%), but overall genetic differentiation in 18 mixed populations of India is higher (2.23%), similar to the largest single study on 16 tribal groups from central India (2.18%). The tribal population of South India shows the highest FST value (4.1%), and this value is similar to a study of the Dhangar caste group. The reason for this high FST value is not clear. One possibility may be (semi-) isolation associated with such factors as random inbreeding and drift, which can cause high levels of genetic differentiation among the tribal groups of India and among the castes such as Dhangar. However, further studies are needed to explore the causes of such high values of genetic differentiation, especially in these populations.

Vitamin D binding protein (DBP) is a major carrier protein for the vitamin D metabolites, but may also play an important role in osteoclast differentiation. Polymorphisms of the DBP gene have been reported, including (TAAA)^sub n^-Alu repeat polymorphisms downstream of intron 8. We have examined the relationship between polymorphisms of the DBP gene and bone mineral density (BMD) and vertebral fractures in a group of 26 men with vertebral fractures but no underlying secondary cause of osteoporosis (median age 64, ages 27-72 years) and 21 male control subjects (median age 65, ages 40-77 years). There was no apparent effect of DBP phenotype on BMD, but there was a relationship between certain genotypes of (TAAA)^sub n^-Alu repeats and reduced BMD and vertebral fracture. Lumbar spine and femoral neck BMD were significantly lower in men with 10/8 genotype than 10/10 genotype (P < 0.05). Furthermore, the predominant genotype in men with vertebral fractures was 10/8, whereas the most common genotype in control subjects was 10/10 (odds ratio 56; 95% confidence interval 7-445). Plasma DBP was higher in men with 10/8 genotype than those with 10/10 genotype (P < 0.05), and patients with vertebral fractures were found to have higher levels than control subjects (P < 0.0005). Although our study is small because of the relative rarity of idiopathic osteoporosis in men, the results suggest that (TAAA)^sub n^-Alu polymorphism may have an important effect on plasma levels of DBP, bone density and fracture risk in men.[PUBLICATION ABSTRACT]

Vitamin D binding protein (DBP) is a major carrier protein for the vitamin D metabolites, but may also play an important role in osteoclast differentiation. Polymorphisms of the DBP gene have been reported, including (TAAA)(n)-Alu repeat polymorphisms downstream of intron 8. We have examined the relationship between polymorphisms of the DBP gene and bone mineral density (BMD) and vertebral fractures in a group of 26 men with vertebral fractures but no underlying secondary cause of osteoporosis (median age 64, ages 27-72 years) and 21 male control subjects (median age 65, ages 40-77 years). There was no apparent effect of DBP phenotype on BMD, but there was a relationship between certain genotypes of (TAAA)(n)-Alu repeats and reduced BMD and vertebral fracture. Lumbar spine and femoral neck BMD were significantly lower in men with 10/8 genotype than 10/10 genotype (P < 0.05). Furthermore, the predominant genotype in men with vertebral fractures was 10/8, whereas the most common genotype in control subjects was 10/10 (odds ratio 56; 95% confidence interval 7-445). Plasma DBP was higher in men with 10/8 genotype than those with 10/10 genotype (P < 0.05), and patients with vertebral fractures were found to have higher levels than control subjects (P < 0.0005). Although our study is small because of the relative rarity of idiopathic osteoporosis in men, the results suggest that (TAAA)(n)-Alu polymorphism may have an important effect on plasma levels of DBP, bone density and fracture risk in men.

The frequencies of the HLA-A, B, C, DR, DQ antigens and of several other genetic markers in biopsy proved and well characterised patients with Wegener's granulomatosis were compared with control frequencies of the region. A highly significant increase in HLA-DR1 was found. The percentage combined frequency of DR1-DQw1 was significantly higher in patients than in the controls. Interestingly, association with the red cell enzyme GLOI and complement locus C4B was also seen. As both of these markers are either linked or within the major histocompatibility complex region (MHC) this is further evidence for the involvement of chromosome 6 in the pathogenesis of Wegener's granulomatosis. To understand the pathology of the disease fully molecular genetic studies of the MHC region are warranted.

Genetic polymorphisms for six blood groups, three red cell enzymes, three serum proteins, and hemoglobin were examined in sixteen central Indian tribal populations. Nine of the tribes belonged to Orissa, five to Madhya Pradesh, and two to Maharashtra. Eleven tribes spoke the Dravidian language, three Indo-Ayran, and two the language of the Austro-Asiatic families. The population structure of these tribal populations was analyzed at the inter-and intrastate and linguistic levels, using data for 13 genetic systems (38 alleles or haplotypes). Nine of the 13 loci showed significant heterogeneity in the 16 tribes, and the pattern of heterogeneity was also discernible in the different states and in the Dravidian-speaking tribes. As expected, the extent of genetic differentiation or gene diversity was the highest so far reported from central India. The mean FIS and Hs for each locus in the different state, linguistic, and total tribal groups were consistently higher than the FST and GST values, respectively, showing that the genetic structure of each tribe is highly influenced by inbreeding. In a genetic affinity analysis by genetic distance the Indo-Aryan and Austro-Asiatic language groups showed little affinity with each other, although there was some tendency toward geographic affinity. The present analysis indicates that, in addition to genetic drift, gene flow, and selection, the genetic structure of the populations of central India is also highly influenced by sociocultural adaptation and inbreeding.

Isoelectric focusing was performed to analyze PGM1 polymorphism in six tribal, five caste, and five Muslim populations from the Indian subcontinent. Although a considerable range of allele frequencies was observed in certain caste and Muslim groups, the phenotypic distribution showed significant genetic heterogeneity only among the tribal groups. Discriminant analysis suggests that the PGM1 locus provides useful anthropogenetic information to differentiate the populations of the subcontinent in terms of their social structure. In the three population groups studied the variation in the heterozygosity levels suggests that the genetic diversity at the PGM1 locus may be the result of the structure of various population groups.