Figure 1. Angiotensin converting enzyme (ACE) genotypes. Poly- merase chain reaction amplification of ACE alleles insertion (I) and deletion (D) showed the presence of 490-bp and 190-bp products on 1.5% agarose gel electrophoresis.

DNA Analysis

We extracted genomic DNA from citrated whole-blood pe- ripheral white blood cells by a modification of previously de- scribed methods (20). Polymerase chain reaction (PCR) was performed to amplify the I/D polymorphic region of the ACE gene as previously described (21). The sense primer was 5’- CTGCAGACCACTCCCATCCTTTCT-3, and the antisense primer was 5’-GATGTGGCCATCACATTCGTCAGAT-3’. The thermal cycling conditions were as follows: initial dena-  nice4° turation at 94 C for 3 minutes followed by 30 cycles at 94 C vi3°C AE2°C for 30 seconds, 63 C for 1 minute, 72 C for 1 minute, and a ~ aN2°C final extension at 72 C for 10 minutes. The PCR products were separated by electrophoresis on a 1.5% agarose gel (Fig- ure 1). Allele frequencies for each group were calculated by chi-square analysis on contingency tables.

((cid:2)2   4.05, p  .04) (Table 3). These results are similar to those previously reported (D allele more frequent in cente- narian than in control: p WEr<. .01) (16).

D ISCUSSION

The genotypes and I/D allele polymorphism of the ACE gene have been reported at different frequencies in different races. The I allele of the ACE gene has a reported frequency of approximately 0.47 in Caucasians (22,23). Barley and col- leagues (23) reported a considerably higher I allele frequency of 0.91 in Polynesian (Samoan) and 0.85 in South American native (Yanomami) populations. The frequency of the I allele in healthy Korean subjects (0.58) was very similar to that in healthy Japanese subjects (0.59) (18,24) and fell between the frequencies reported for Caucasians, Samoans, and Ya- nomami. In our study, there were no marked differences in ge- notype or allele frequencies between the three racial groups, and the frequency of the I allele (0.645) was closer to that of the Koreans and Japanese than that of the Caucasians, Samo- ans, or Yanomami. It is possible, though only speculative, that this may reflect a similarity among Asians in general.

R ESULTS

The frequencies of genotypes and alleles of the I/D poly- morphism of the ACE gene in the three races are shown in Table 2. There were no significant differences between the groups in the overall distribution of genotypes ((cid:2)2  4.6, p   .33) and alleles ((cid:2)2   1.3, p aaa. .51). Frequencies of the I and D alleles were 0.645 (156/242) and 0.355 (86/242), re- spectively, in the control group and 0.552 (117/212) and 0.448 (95/212), respectively, in the Uighur longevity group

The differences in the ACE polymorphism between pop- ulations may be due to differences in genetic background

1. Characteristics of the Study Populations

Sex Group Region Race n Age Range (y) Male (n) Female (n) ULH Hotan Uighur 106 90–113 (93.7  4.3) 71 35 UOH Hotan Uighur 121 59–70 (66.6   2.9) 80 41 HOH Hotan Han 38 65–70 (67.7  1.5) 24 14 KOB Balkun Kazakh 108 65–70 (67.3 3+ 2  2.0) 38 70 HOB Balkun Han 51 65–70 (66.7  1.9) 21 30

Table 2. Distribution of the Insertion/Deletion Polymorphism of the Angiotensin-Converting Enzyme Gene in the Three Races Studied

Genotype (%) Allele (%) Race n Age Range (y) I/I I/D D/D I D Uighur 98 65–70 (67.4 It 1.7) 37.5 53.1 9.2 64.3 35.7 Kazakh 108 65–70 (67.3 3 +2 2.0) 38.0 45.4 16.7 60.7 39.4 Han 89 65–70 (67.2   1.4) 42.7 46.1 11.2 65.7 34.5 p Value .37 .51

Notes: ULH   Uighur longevity group in Hotan; UOH   Uighur older group in Hotan; HOH  Han older group in Hotan; KOB   Kazakh older group in Balkun; HOB  Han older group in Balkun. Values in parenthe- ses are means  SEM.

Note: I   insertion; D   deletion.

Table 3. Distribution of the Insertion/Deletion Polymorphism of the Angiotensin-Converting Enzyme Gene in Uighur Control and Longevity Groups

Total Male Female Parameter Control Longevity Control Longevity Control Longevity Genotype I/I 48 (39.7%) 29 (27.4%) 33 (41.3%) 23 (32.4%) 15 (36.6%) 6 (17.1%) I/D 60 (49.6%) 59 (55.7%) 40 (50%) 37 (52.1%) 20 (48.8%) 22 (62.9%) D/D 13 (10.7%) 18 (17%) 7 (8.8%) 11 (15.5%) 6 (14.6%) 7 (20%) p Value .104 .32 .17 Allele I 156 (64.5%) 117 (55.2%) 106 (66.3%) 83 (58.4%) 32 (39%) 34 (48.6%) D 86 (35.5%) 95 (44.8%) 54 (33.8%) 59 (41.6%) 50 (61%) 36 (51.4%) p Value .04 .16 .13 Fisher’s .05 .19 .14

Notes: I   insertion; D   deletion. Populations are in Hardy-Weinberg equilibrium for the ACE gene.