Association of HLA-DRB1, DQA1 and DQB1 alleles and haplotype in Parkinson's disease from South India.

Parkinson's disease (PD) is a chronic, neurodegenerative motor disease exhibiting familial and sporadic forms. The present study was aimed to elucidate the association of HLA-DRB1*, DQA1* and DQB1* alleles with PD. A total of 105 PD patients and 100 healthy controls were typed by PCR-SSP method. We further carried out high-resolution genotyping for DQB1 and DQA1. Results revealed the increased frequencies of alleles DRB1*04 (OR = 2.36), DRB1* 13 (OR = 4.04), DQA1* 01:04:01 (OR = 4.51), DQB1*02:01 (OR = 2.66) and DQB1*06:03 (OR = 2.65) in PD patients suggesting susceptible associations. Further, decreased frequencies observed for alleles DRB1*10 (OR = 0.34), DRB1*15 (OR = 0.44), DQA1*04:01 (OR = 0.28), DQA1*06:01 (OR = 0.11) and HLA-DQB1*05:01 (OR = 0.37) among patients have suggested protective associations. Significant disease associations were observed for two-locus haplotype such as DRB1*13-DQB1*06:03 (OR = 11.52), DQA1*01:041-DQB1*06:03 (OR = 16.50), DQA1*01:041-DQB1*05:02 (OR = 5.38) and DQA1*04:01-DQB1*06:03 (OR = 3.027). Protective associations were observed for haplotypes DRB1*10-DQB1*05:01 (OR = 0.21), DRB1*15-DQB1*06 (OR = 0.006), DQA1*04:01-DQB1*05:01 (OR = 0.400) and DQA1*04:01-DQB1*05:03 (OR = 0.196). The critical amino acid residue analyses have revealed strong susceptible association for the residues of DQB1 alleles such as: L26, S28, K71, T71 and A74, Y9, S30, D37, I37, A38, A57 and S57; and for the residues of DQA1 alleles such as: C11, F61, I74, and M76. Similarly, amino acid residues such as A13, G26, Y26, A71, S74, L9 and V38 of HLA-DQB1 alleles and residues such as Y11, G61, S74 and L76 of DQA1 alleles showed protective associations. Thus, our study documented the susceptible and protective associations of DRB1*, DQB1 and DQA1 alleles and haplotypes in developing the disease and their influence on longevity of PD patients in south India.

HLA-DRB1 genes and the expression dynamics of HLA CIITA determine the susceptibility to T2DM.

Type 2 diabetes mellitus (T2DM) is a disease with polygenic inheritance. The expression of major histocompatibility complex class II genes are regulated by several trans-activators. We have studied the expression of HLA-DRB1, RFX, CIITA-P1, PIV transactivators, immunophenotyping of cells, SNPs in CIITA-168 (A/G) and IFN-γ + 874 (T/A) in T2DM patients and controls (n = 201 each). We observed increased frequencies of DRB1*03, DRB1*04 and DRB1*07 and decreased frequencies of DRB1*10, DRB1*14, and DRB1*15 alleles among patients. Significant up-regulations of HLA-DRB1 genes were observed in patients (p < 0.0001). Down-regulated expressions were documented in DRB1*03-homo (p < 0.002) and DRB1*04-homo (p < 0.009) patients. No significant differences were observed for CIITA-P1 expression except DRB1*04-pooled (p < 0.0113). The CIITA-PIV was up-regulated in overall (p < 0.0001), DRB1*03-pooled (p < 0.0006), DRB1*03-hetero (p < 0.0006) and DRB1*03-homo (p < 0.001) T2DM patients. However, significant down-regulations were documented for DRB1*04-pooled (p < 0.040), DRB1*04-hetero (p < 0.060), and DRB1*04-homo (p < 0.027) combinations. Further, significant down-regulations of RFX5 were observed in overall (p < 0.0006), DRB1*04-pooled (p < 0.0022), and DRB1*04-hetero (p < 0.0004) combinations. Immunophenotyping studies revealed significant increase of CD45+ CD14-, CD19+, CD14- and CD8 cells and elevated level of expression of IFN-γ (p < 0.0001) in patients. A significant increase of TT (p < 3.35 × 10-6) and decrease of TA (p < 4.57 × 10-4) genotypes of IFN-γ + 874 (T/A) and an increase of GG (p < 0.001) and decrease of AG (p < 8.24 × 10-5) genotypes of CIITA-168 A/G SNPs were observed. The combinatorial analysis revealed susceptible associations for DRB1*03 + AA, *03 + AG, *03 + GG and *04 + GG and protective associations for DRB1*10 + AG, *10 + GG, *15 + AG, and *14 + GG combinations. Thus, the present study corroborated the effect of differential expressions of promoters of risk alleles in the pathogenesis of T2DM.

HLA-DRB1* and DQB1* allele and haplotype diversity in eight tribal populations: Global affinities and genetic basis of diseases in South India.

The distribution of HLA class-II DRB1* and DQB1* alleles/ haplotypes were studied in 438 individuals of 8 Dravidian tribal groups inhabiting the Western Ghats, south India. The HLA typing was performed by PCR-SSP method. In order to identify the 5-locus Ancestral Extended Haplotypes (AEH), the alleles of HLA-A, -B and -C loci were typed for DNAs with predominant 2-locus haplotypes. The analyses have revealed allele HLA-DRB1*15 as the most predominant allele (Lowest / Highest range: Urali, 14.81 / Malasar, 48.94), followed by the alleles DRB1*10 (Katunayakan, 1.85 / Paliyan, 48.21), DRB1*14 (Paliyan 4.46 / Katunayakan, 40.74), DRB1*12 (Mannan, 1.64 / Katunayakan, 20.37) and DRB1*03 (Mannan, 1.64 / Urali, 29.63). The most frequent DQB1* alleles were DQB1*02 (Paliyan 3.57 / Urali, 23.15), DQB1*05 (Katunayakan, 27.77 / Paliyan 84.82) and DQB1*06 (Malasar, 8.51 / Kuruman, 33.51). The most predominant two-locus haplotypes observed were DRB1*15-DQB1*05, DRB1*10-DQB1*05, DRB1*15-DQB1*06 and DRB1*04-DQB1*05. The present study of HLA immunogenetics of south Indian tribes have revealed the presence of globally shared two and 5-locus haplotypes. Many of these haplotypes were implicated in a number of diseases in south India. We observed the presence of ancestral extended haplotypes (AEHs), hitherto not reported in Indian populations such as, A*68-B*35-C*02-DRB1*15:01-DQB1*05:01, A*24-B*57-C*06-DRB1*04:01-DQB1*05:01 and A*24-B*35-C*02-DRB1*15:01-DQB1*05:02. The dendrogram based phylogenetic analyses have revealed the Caucasian affinity of Urali, palaeo-Mediterranean and Indo-European affinity of Malasar tribes. The presence of globally shared susceptible and protective haplotypes reiterated the mosaic immunogenetic fabric of south Indian tribes.

Association of slow acetylator genotype of N-acetyltransferase 2 with Parkinson's disease in south Indian population.

AIM: Parkinson's Disease (PD) is a neurodegenerative disorder with predisposing genetic and environmental factors. The present study was undertaken to elucidate the possible association of NAT2 gene polymorphism in PD patients from south India. METHODS: Using previously validated PCR-RFLP assays, we genotyped 105 PD subjects and 101 healthy controls for N-acetyl transferase (NAT2) gene polymorphism. RESULTS: We observed a significantly elevated frequencies of NAT2 *5/6 (OR = 4.21; p < 0.029) and *5/7 (OR = 2.73; p < 0.025) genotypes and NAT2*5 (OR = 1.83; p < 0.039) allele among PD cases showing susceptible associations. The age at onset analysis revealed a significant association of NAT2 *4/6 (OR = 4.62; p < 0.05) genotype with early onset PD (EOPD). A positive association with early onset disease was observed for *5/7 (OR = 3.88; p < 0.075) genotype, however without statistical significance. Whereas, in late onset PD (LOPD) cases, significant susceptible association was observed for NAT2 *5/7 (OR = 5.27; p < 0.029) genotype. We observed a highly significant protective association of NAT2 *4/6 (OR = 0.27; p < 0.012) genotype and NAT2 *4 (OR = 0.52; p < 0.027) allele with LOPD. The acetylator status phenotype analysis have revealed a higher risk for, 'NAT2 slow acetylator' in both overall PD (OR = 2.39; p < 0.002) and LOPD (OR = 2.88; p < 0.007). However, 'NAT2 intermediate acetylator' with a lower risk in both overall PD (OR = 0.47; p < 0.011) and LOPD (OR = 0.36; p < 0.007) cases revealed protective associations. CONCLUSIONS: Thus, our results revealed the possible susceptible association of NAT2 slow acetylator in PD pathogenesis in south Indian population.

Association of HLA class II alleles/haplotypes and amino acid variations in the peptide binding pockets with rheumatoid arthritis.

BACKGROUND: Rheumatoid arthritis (RA) is an autoimmune, inflammatory disease, caused by environmental and genetic factors. AIM: To elucidate the association of human leukocyte antigen (HLA)-DRB1*/DQB1* alleles/haplotypes and the variations of polymorphic amino acid changes in peptide binding pockets in RA patients from south India. METHODS: HLA typing was performed in 176 RA patients and 176 healthy controls by polymerase chain reaction-sequence-specific primers method. RESULTS: Strong susceptible association for alleles such as DRB1*04:01(odds ratio [OR] = 3.66), 04:06 (OR = 3.81), 03:01 (OR = 2.93), 06:01 (OR = 2.53) and protective association for alleles such as DRB1*13:01 (OR = 0.17), 14:01 (OR = 0.15), 05:02 (OR = 0.17), and 05:03 (OR = 0.338) were observed in RA patients. The 2-locus haplotypes such as 04-02:01 (OR = 3.844), 04-06:01 (OR = 6.57), 07-03:01 (OR = 6.16), 07-06:01 (OR = 3.42), 12-06:01 (OR = 5.24), 15-03:01 (OR = 4.69) with susceptible and DRB1*14-DQB1*05:03 (OR = 0.078) with protective associations were observed in RA patients. The acid-base analysis revealed that the basic group BB allele was positively associated (OR = 2.372) and the acidic group AA allele was negatively associated (OR = 0.086). The analysis on shared epitopes has revealed that the combination QKRAA+, (Q)RRAA+ or (Q)RRAA- was positively associated with RA (OR = 2.78). The amino acid variation at HLA-DQß molecule revealed susceptible associations for residues E86 and L87 (P1); E74 (P3); A13 , Y26 , I/S28 , T28 , I71 and E74 (P4); L9 , T30 , D37 and D57 (P9), whereas, the amino acids A86 and T87 (P1); S74 (P3); G13/26 , A71 and S74 (P4); H30 and T37 , S57 (P9), showed protective associations. CONCLUSIONS: Alleles DRB1*04:06 and*04:01 showed strong susceptible and DRB1*13:01 and *14:01 showed protective associations in RA patients. The amino acid variations in DQß molecules revealed significant molecular markers for susceptibility to and protection from RA in south India.

Diversity and association of HLA/KIR receptors with type 2 diabetes in South India.

The present study was undertaken to delineate the association(s) of KIR-HLA combination in South Indian Type 2 diabetes mellitus (T2DM) patients. The T2DM patients (n = 343) and healthy controls (n = 309) were genotyped for KIR/HLA ligands by PCR-SSP method. The increased frequency of activatory KIR (aKIR) 2DS2 (OR = 1.91; p < 2.91 × 10-4 ) was observed in patients suggesting a susceptible association. The frequencies of iKIR 2DL2 (OR = 0.38; p < 1.55 × 10-5 ) and aKIRs 2DS1 (OR = 0.60; p < 0.001) and 3DS1 (OR = 0.52; p < 5.83 × 10-5 ) were decreased in patients suggesting protective associations. The C1/C2 combinatorial analysis has revealed an increased frequency of C1+ /C2- in T2DM patients (OR = 1.62; p < 0.014). The KIR "AB" genotype (OR = 2.41; p < 3.87 × 10-5 ) was observed to be higher in patients. However, the "BB" genotype (OR = 0.32; p < 4.71 × 10-7 ) was increased in controls. The KIR motifs, "Tel-B/B" (OR = 1.84; p < 0.007), were observed higher among patients. However, the frequency of "Tel-A/B" motif genotype was decreased in patients (OR = 0.56; p < 3.13 × 10-4 ). The iKIR/HLA combinations such as 2DL2/3 +C1 and 3DL2+A3/A11 were increased in patients (OR = 3.90; p < 7.5 × 10-5 ) suggesting susceptible associations. On the contrary, the aKIR+HLA combinations such as 2DS2+C1, 2DS1+C2 and 3DS1+Bw4 were less frequent in patients (OR = 0.32; p < 4.2 × 10-4 ) suggesting protective associations. Thus, the present study clearly establishes the positive and negative associations of different KIR-HLA receptor combinations with T2DM in South India.

Effect of angiotensin converting enzyme gene I/D polymorphism in South Indian children with nephrotic syndrome.

Nephrotic syndrome is one of the most common childhood kidney diseases. It is mostly found in the age group of 2 to 8 years. Around 10%-15% of nephrotic syndrome cases are non-responders of steroid treatment (SRNS). Angiotensin converting enzyme (ACE) (I/D) gene association studies are important for detecting kidney disease and herein we assessed the association of ACE (I/D) polymorphism with nephrotic syndrome in South Indian children. We recruited 260 nephrotic syndrome (162 boys and 98 girls) and 218 (140 boys and 78 girls) control subjects. ACE I/D polymorphism was analyzed by PCR using genotype allele specific primers. In ACE (I/D), we did not find significant association for the ungrouped data of nephrotic syndrome children and the control subjects. Kidney biopsies were done in 86 nephrotic syndrome cases (minimal change disease, n=51; focal segmental glomerulosclerosis, n=27; diffuse mesangial proliferation, n=8). We segregated them into the minimal change disease / focal segmental glomerulosclerosis groups and observed that the ACE'D' allele was identified with borderline significance in cases of focal segmental glomerulosclerosis and the 'I' allele was assessed as having very weak association in cases of minimal change disease. 'II' genotype was weakly associated with minimal change disease. Gender specific analysis revealed weak association of 'ID' genotype with female nephrotic syndrome in females. Dominant expression of DD genotype was observed in males with nephrotic syndrome. Our finding indicated that ACE (I/D) has moderate association with focal segmental glomerulosclerosis. However, due to the limited number of biopsy proven focal segmental glomerulosclerosis subjects enrolled, further studies are required to confirm these results.

Predisposition of Angiotensin-converting Enzyme Deletion/Deletion Genotype to Coronary Artery Disease with Type 2 Diabetes Mellitus in South India.

BACKGROUND: Worldwide, South Asians contribute to a high proportion of coronary artery disease (CAD) burden, mainly attributed to a high prevalence of diabetes. Early identification of such high-risk individuals would enable aggressive disease modification and prevention of complications. Definition of susceptible genotypes early in the course of disease may be one such avenue for reduction in morbidity and mortality from CAD. AIM: Our study was aimed to investigate the insertion/deletion polymorphism of angiotensin-converting enzyme (ACE I/D) gene and susceptibility to CAD in patients with type 2 diabetes mellitus (T2DM) in a South Indian population. SUBJECTS AND METHODS: ACE (I/D) genotyping was performed by polymerase chain reaction specific primer for 187 CAD patients and 185 age- and sex-matched controls. RESULTS: We observed that the ACE"II" genotype was found to be significantly associated with CAD patients (odds ratio [OR] = 1.689; P = 0.028). However, multiple logistic regression analysis revealed that ACE "DD" genotype was found to be most predominant risk factor for CAD patients with T2DM (OR = 6.118; P = 0.001). CONCLUSION: Our results showed that ACE (I/D) genotypes and alleles presented functional dimorphism in the development of CAD and CAD with T2DM patients in South India. This finding may be extremely useful in identifying subsets of patients where early aggressive treatment of risk factors is warranted.

Correction: Polymorphic Alu Insertion/Deletion in Different Caste and Tribal Populations from South India.

[This corrects the article DOI: 10.1371/journal.pone.0157468.].

Association of HLA-A, B, DRB1* and DQB1* alleles and haplotypes in south Indian T2DM patients.

The genes of Human Leukocyte Antigen (HLA) system are implicated in the susceptibility of several diseases including Type 2 diabetes (T2DM). Therefore, we aimed to investigate the association of HLA alleles with T2DM in south India. A total of 344 patients (195 males; 149 females) and 309 controls (186 males; 123 females) were genotyped for HLA-DR/-DQ alleles. Based on predominant DR/DQ haplotypes, 222 patients and 222 age/sex matched controls were HLA-A/-B genotyped. HLA alleles were typed by PCR-SSP methods. Susceptible association was observed for the alleles A*33 (OR=13.8), A*01 (OR=3.69), A*02 (OR=2.91), B*07 (OR=4.12), DRB1*11 (OR=2.23), DRB1*04 (OR=1.51), DRB1*03 (OR=1.90) and DQB1*02 (OR=1.49). Protective association was observed for the alleles A*11 (OR=0.59), A*68 (OR=0.68), B*40 (OR=0.50), B*54 (OR=0.42), B*57 (OR=0.31), B*51 (OR=0.29) and DRB1*10 (OR=0.45). Gender stratified analysis too confirmed many of these associations. Predominant susceptible haplotypes were A*33-B*40 (OR=10.27), A*01-B*07 (OR=4.97), A*02-B*07 (OR=6.50), DRB1*03-DQB1*05 (OR=1.88), DRB1*03-DQB1*06 (OR=3.01), DRB1*04-DQB1*05 (2.63), A*01-B*07-DRB1*10 (OR=8.26) and A*11-B*35-DRB1*07 (OR=9.338). Haplotypes A*03-B*07 (OR=0.57; p<0.034) and DRB1*10-DQB1*05 (OR=0.57; p<0.033) were protectively associated. Further, a very strong susceptible association was documented for four-locus haplotypes such as A*11-B*40-DRB1*15-DQB1*06 (n=15; OR=16.01; p<0.001); A*01-B*07-DRB1*10-DQB1*05 (n=8; OR=8.26; p<0.043) and A*11-B*07-DRB1*07-DQB1*05 (n=8; OR=8.26; p<0.043). Thus, a number of HLA alleles and haplotypes showed susceptible and protective association(s) in T2DM patients from south India.

MTHFR (C677T) CT genotype and CT-apoE3/3 genotypic combination predisposes the risk of ischemic stroke.

The predisposition to ischemic stroke (IS) might involve interactions of several genes and environmental factors. The present study was aimed to evaluate the influence of polymorphisms in methylenetetrahydrofolate reductase (MTHFR-C677T) and apolipoprotein-E (apo-E) as risk factors for IS patients in south Indian population. 200 IS patients and 193 age and sex matched controls were genotyped for MTHFR-C677T and apoE by Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) method. Statistically significant association was observed for MTHFR CT genotype (IS-Pooled: OR=4.29; p=5.01×10(-5); IS-Males: OR=4.13; p=0.001; IS-Females: OR=8.62; p=0.027; IS-Large Vessel Disease (LVD)- Pooled: OR=4.14; p=0.0002) and T allele (IS-Pooled: OR=4.82; p=1.49×10(-5); IS-Males: OR=4.33; p=0.0002; IS-Females: OR=7.99; p=0.031; IS-LVD-Pooled: OR=4.13; p=0.0001). Further, reduced frequencies of CC genotype (IS-Pooled: OR=0.20; p=9.80×10(-6); IS-Males: OR=0.25; p=0.001; IS-Females: OR=0.12; p=0.027; IS-LVD-Pooled: OR=0.23; p=0.0001) and C allele (IS-Pooled: OR=0.21; p=1.49×10(-5); IS-Males: OR=0.23; p=0.0002; IS-Females: OR=0.13; p=0.031; IS-LVD-Pooled: OR=0.24; p=0.0001) were observed in IS patients than the controls. No association was observed for apoE genotypes/alleles in IS/LVD cases. Our study demonstrated the presence of risk for MTHFR CT genotype/T allele and 'CT-3/3' (n=33 vs. 5; OR=7.42; p=0.001) genotypic combination in the development of IS in south India. Further, follow-up study of these stroke cases i.e., in later stages of the disease whether they are developing the neurological disorders such as Alzheimer's Disease (AD) and vascular dementia (VaD) is needed to draw a fruitful conclusion in connection between neurological disorders and with these two polymorphisms, before translating it into clinical practice.

Polymorphic Alu Insertion/Deletion in Different Caste and Tribal Populations from South India.

Seven human-specific Alu markers were studied in 574 unrelated individuals from 10 endogamous groups and 2 hill tribes of Tamil Nadu and Kerala states. DNA was isolated, amplified by PCR-SSP, and subjected to agarose gel electrophoresis, and genotypes were assigned for various Alu loci. Average heterozygosity among caste populations was in the range of 0.292-0.468. Among tribes, the average heterozygosity was higher for Paliyan (0.3759) than for Kani (0.2915). Frequency differences were prominent in all loci studied except Alu CD4. For Alu CD4, the frequency was 0.0363 in Yadavas, a traditional pastoral and herd maintaining population, and 0.2439 in Narikuravars, a nomadic gypsy population. The overall genetic difference (Gst) of 12 populations (castes and tribes) studied was 3.6%, which corresponds to the Gst values of 3.6% recorded earlier for Western Asian populations. Thus, our study confirms the genetic similarities between West Asian populations and South Indian castes and tribes and supported the large scale coastal migrations from Africa into India through West Asia. However, the average genetic difference (Gst) of Kani and Paliyan tribes with other South Indian tribes studied earlier was 8.3%. The average Gst of combined South and North Indian Tribes (CSNIT) was 9.5%. Neighbor joining tree constructed showed close proximity of Kani and Paliyan tribal groups to the other two South Indian tribes, Toda and Irula of Nilgiri hills studied earlier. Further, the analysis revealed the affinities among populations and confirmed the presence of North and South India specific lineages. Our findings have documented the highly diverse (micro differentiated) nature of South Indian tribes, predominantly due to isolation, than the endogamous population groups of South India. Thus, our study firmly established the genetic relationship of South Indian castes and tribes and supported the proposed large scale ancestral migrations from Africa, particularly into South India through West Asian corridor.

Association of HLA-DR/DQ alleles and haplotypes with nephrotic syndrome.

BACKGROUND: Nephrotic syndrome (NS) is a debilitating renal problem in children resulting from an interaction between environmental and genetic factors including human leukocyte antigen genes (HLA). The aim of this work was to study the probable link between HLA alleles/haplotypes and NS in south India. METHODS: HLA DRB1*/DQB1* alleles were genotyped in 183 NS (76 steroid sensitive-SSNS; 107 steroid resistant-SRNS) and paediatric healthy controls (PHCs; n = 91) using polymerase chain reaction-sequence specific primers (PCR-SSP). HLA-A/-B genotyping was performed for patients (n = 70) positive for DRB1*07-DQB1*02 haplotype to identify four locus extended haplotype. RESULTS: The following alleles and haplotypes were strongly associated with NS (P < 0.05 as significant): DRB1*07 (SSNS, P < 7.98 × 10(-6) ; SRNS, P < 0.008), DQB1*02 (SSNS, P < 3.99 × 10(-6) ; SRNS, P < 0.002), DRB1*07-DQB1*02 (SSNS, P < 1.32 × 10(-4) ; SRNS, P < 0.010), DRB1*07-DQB1*0301,0304 (DQ7) (SSNS, P < 0.001) and DRB1*03-DQB1*02 (SRNS, P < 0.048). Protective associations were observed for alleles DRB1*10 (SRNS, P < 0.013), DQB1*05 (SSNS, P < 4.34 × 10(-6) ; SRNS, P < 0.01), DQB1*06 (SSNS, P < 0.003), and haplotypes DRB1*10-DQB1*06 (SSNS, P < 0.046; SRNS, P < 0.032) and DRB1*15-DQB1*05 (SSNS, P < 0.018). HLA-A/-B typing of 70 NS cases with two locus haplotype DRB1*07-DQB1*02 (70/183; 38.25%) revealed the presence of an extended haplotype 'A*03-B*07-DRB1*07-DQB1*02' (n = 35; 50%). CONCLUSION: Our study revealed strong susceptible association of DRB1*07 with SRNS and DQB1*02 with SSNS. A gender predominant protective association was observed for DRB1*10 with SRNS females; DQB1*05 with SSNS and SRNS males. Further, the study documented the presence of an extended haplotype and pleiotropic action of DRB1*/DQB1* alleles in immune-mediated aetiology of NS in south India.

ACE-II genotype and I allele predicts ischemic stroke among males in south India.

Two hundred ischemic stroke patients and 193 age and sex matched healthy controls were studied for the presence of Angiotensin Converting Enzyme Insertion/Deletion (ACE I/D) gene polymorphism. The PCR studies revealed that ACE 'II' (OR = 2.055; p = 0.004) genotype and 'I' (OR = 1.411; p = 0.018) alleles were significantly associated with IS patients. Gender specific analysis revealed a strong association of 'II' (OR = 2.044; p = 0.014) genotype and 'I' (OR = 1.531; p = 0.011) allele with male sex. Classification of patients based on TOAST criteria, revealed a significant association for 'II' genotype (OR = 1.713; p = 0.043) and 'I' (OR = 1.382; p = 0.039) allele in LVD patients only. When the data was stratified based on age and sex, a statistically significant association was observed for ACE 'II' genotype (OR = 2.288; p = 0.006) and 'I' allele (OR = 1.395; p = 0.054) in IS male patients of > 50 years of age. The ACE 'D' allele was found to be increased in controls (OR = 0.709; p = 0.018) than IS patients. Multivariate logistic regression analysis showed that smoking and diabetes were the most powerful independent risk factor in LVD type of stroke. Thus, we presented here an evidence for a strong association of ACE 'II' genotype and 'I' allele compounded by factors such as smoking and diabetes among south Indian IS patients.