Abstract
Insofar as genetic susceptibility to type 1 diabetes is associated with HLA class II genes, with certain allelic combinations conferring disease susceptibility or resistance, this study assessed the distributions of HLA-DR and -DQ among 107 unrelated patients with type 1 diabetes and 88 healthy controls from Bahrain, all of Arab origin. The HLA
-
DRB and -DQB genotypes were determined by PCR-sequence-specific priming. The following alleles showed the strongest association with type 1 diabetes among patients versus controls according to their frequencies:
DRB1
*
030101
(0.430 versus 0.097;
P
< 0.001),
DRB1
*
040101
(0.243 versus 0.034;
P
< 0.001),
DQB1
*
0201
(0.467 versus 0.193;
P
< 0.001), and
DQB1
*
0302
(0.229 versus 0.091;
P
< 0.001). When the frequencies of alleles in controls were compared to those in patients, negative associations were seen for
DRB1
*
100101
(0.085 versus 0.014;
P
< 0.001),
DRB1
*
110101
(0.210 versus 0.060;
P
< 0.001),
DQB1
*
030101
(0.170 versus 0.075;
P
= 0.006), and
DQB1
*
050101
(0.335 versus 0.121;
P
< 0.001). In addition, the
DRB1
*
030101
-
DQB1
*
0201
(70.1 versus 22.7%;
P
< 0.001) and
DRB1
*
030101
-
DQB1
*
0302
(21.5 versus 0.0%;
P
< 0.001) genotypes were more prevalent among patients, thereby conferring disease susceptibility, whereas the
DRB1
*
100101
-
DQB1
*
050101
(20.5 versus 2.8%;
P
< 0.001),
DRB1
*
110101
-
DQB1
*
030101
(28.4 versus 8.4%;
P
< 0.001), and
DRB1
*
110101
-
DQB1
*
050101
(30.7 versus 0.9%;
P
< 0.001) genotypes were more prevalent among controls, thus assigning a protective role. These results confirm the association of specific HLA-DR and -DQ alleles and haplotypes with type 1 diabetes and may underline several characteristics that distinguish Bahraini patients from other Caucasians patients.