The allelic frequencies differed numerically between the active TB patients and the household contacts. In the active group the following HLA alleles were the most common: HLA-A*02 (20.31 %), A*03 (12.50 %), A*30 (10.94 %), A*74 (10.94), HLA-B*15 (23.44 %), B*58 (14.06 %) and B*42 (7.81 %) and HLA-C*03 (20.31 %), C*07 (18.75 %) and C*04 (10.94 %). The following HLA alleles were most common in the household contacts: HLA-A*02 (24.44 %), A*01 (12.22 %) and A*74 (10 %), HLA-B*58 (15.56 %), B*15 (15.56 %) and B*44 (8.89 %) and C*07 (18.89 %), C*04 (17.78 %), and C*03 (15.56 %). (Additional file
3: Table S3) shows the allelic frequencies of the 2 groups and the p values. There was no statistically significant difference concerning the expression of different HLA alleles between the two groups except for the HLA-A*03 allele (12.50 % versus 2.22 %) (
p = 0.017; OR = 6.29, 95 % CI 1.29-30.68) however after Benjamini-Hochberg (FDR) adjustment
p = 0.374. After adjusting for age between the two groups for the HLA-A*03 allele
p = 0.016; OR = 11.67, 95 % CI 1.58-86.26 and after Benjamini-Hochberg (FDR) adjustment
p = 0.176. Despite the loss of statistical significance, 8out of 32 active TB patients had the HLA-A*03 allele but only two of the household contacts out of 45 had the HLA-A*03 allele - this allele needs to be looked further in a study with a larger sample size before drawing any firm conclusions. A study carried out in 1990 showed that A*03 had a positive association with TB in the Kazakh although it had no significance in the other Soviet groups or was not present in their HLA genotype [
14]. This same allele had no positive association in Iraqi and Indian PTB patients [
23,
24].