Plasma total cholesterol (TC), triglycerides (TG), high density lipoprotein cholesterol (HDLC) and apolipoproteins Al (apo Al) and B (apo B) were measured in a sample of subjects from the Semai tribe of Orang Asli in peninsular Malaysia. They appeared to exhibit the lowest TC ever recorded (1.6 for males and 1.9 mmol/l for females) and relatively high TG (1.4 mmol/l for males and 1.5 mmol/l for females)(means for the whole sample). There was little apparent aging gradient in any of the plasma analytes. but the group of men aged 21-40 had lower HDLC than the corresponding female group. Both low density lipoprotein cholesterol (LDLC) (calculated) and HDLC as well as their corresponding apolipoproteins were correspondingly very low. There was a significant correlation between apo AI and HDLC in both sexes.
Members of the Semai group of Orang Asli ('aborigines') in peninsular Malaysia were examined for apolipoprotein E (apo E) variants in relation to plasma total cholesterol (TC), high density lipoprotein cholesterol, low density lipoprotein cholesterol (LDLC), triglycerides (TG), apolipoprotein AI and apolipoprotein B (apo B). The e2 and e4 alleles were found to be higher than in most other groups as reported. The sample as a whole was normotriglyceridaemic (mean plasma TG, 1.5 mmol/l) and very markedly hypocholesterolaemic (mean plasma TC 1.7 mmol/l). The distribution of apo E variants was not related to any of the plasma lipids or apolipoprotein fractions using results from all subjects, but if a distinctly hypertriglyceridaemic sub-section was omitted (TG > 1.7 mmol/l) then apo E variants were determinants of plasma TC, LDLC, and apo B concentrations, the lower values of these being associated with the 2-2 and 2-3 genotypes, and the higher with 3-4, and 4-4.
Associations among seven apolipoprotein B (APOB) gene polymorphisms [C-T promoter site; Leu-Ala-Leu signal peptide (SP) insertion/deletion; AG C,G site at codon 71; AG A1,D site at codon 591; XbaI site at codon 2488; AG H,I site at codon 3611; and AG T,Z site at codon 4154] were investigated in 195 members of an Orang Asli (aborigine) population from western Malaysia. Frequencies of the rare alleles for all these polymorphisms turned out to be low when compared with European but not Asian populations. The AG H,I site was not polymorphic. The highly polymorphic sites are in linkage disequilibrium among themselves, as shown by their delta values: SP 24,27 and AG C,G, 0.68; SP 24,27 and AG A1,D, 0.71; XbaI and AG C,G, 0.64; XbaI and AG A1,D, 0.57; SP 24,27 and XbaI, 0.48; and AG C,G and AG A1,D, 0.68. Ten unequivocal haplotypes on the basis of six sites (excluding the promoter polymorphism) were observed, and they represent 80% of the sample. The frequency of haplotype SP27,G,A1,X-,I,T, defined by the common homozygotes at all the sites for the APOB gene was 0.7, compared with 0.22 in Europeans. The ancestral haplotype SP27,G,D,X-,I,T was present at low frequency (0.01) in both the Orang Asli and Europeans. A cladogram constructed on the basis of haplotypes in the Orang Asli shows two different lines of evolution and that other haplotypes evolved by subsequent mutations on the ancestral haplotype.