Genetic markers for insulin-dependent diabetes mellitus in Japanese

Diabetes Research and Clinical Practice, 24 Suppl. (1994) S83-S87

Genetic markers for insulin-dependent Japanese

diabetes mellitus in

Takuya Awata* a, Y asunori Kanzawab “Department of Pathology, University of Massachusetts Medical Center, Worcester, Massachusetts, USA bOmiya Medical Center, Jichi Medical School Omiya, Japan

Abstract &though the KL4 class I1 genes are clearly associated with insulin-dependent diabetes mellitus (IDDM) in all ethnic groups, considerable variation in the associated haplotypes is sbserved among the ethnic groups. In Japanese, DRBI*O405~DQAl*0301DQBl* 0401, DRBl* 0901-DQAl* 0301~DQBl* 0303 and DRBl* 0802-DQAP 0301DQB1*0302 are the major susceptibility haplotypes to IDDM, while DRBl* UOl-DQAl* 0102-DQBl* 0602 and DRBl* 1502-DQAl* 0103-DQBP 0601 are the major resistance haplotypes. The hypothesis that alleles encoding amino acids obter than aspartic acid at the DQBl position 57 contribute to IDDM susceptibility is not applicable to the Japanese, mainly because the first and second sJsceptrbiIity haplotypes listed above have aspartic acid at DQBl position 57. In the 5’ insulin gene polymorphism, the shorter insertion Wass 1 allele) is predominant, and is not associated with diabetes in Japanese. Subdivision of the class 1 alleles also fai!ed to show an association with IDDM in Japanese. The insulin gene region appeared to be of less value as a genetic marker for IDDM in Japanese. Little is known about other genetic markers. E@ywordr: Genetic markers for IDDM; HLA class II genes; DR-DQ haplotypes; Variable number tandem repeat; Insulin gene

1. Introduction

In recent years, a number of studies analyzed the HL4 class II genes associated with insulin-dependent diabetes mellitus (IDDM) and revealed susceptibility and resistance alleles, haplotypes and genotypes in several ethnic groups including Caucasians, Blacks and Japanese [I]. Todd et al. 121 proposed that alleles encoding amino acids other than aspartic acid at DQBl position 57 contribute to IDDM susceptibility. This hypothesis, however, does not apply to the Japanese.

*Corresponding author.

Many Japanese IDDM patients as well as nondiabetic subjects have the alleles for aspartic acid at DQBl position 57 [3-51. Subsequent studies [6,7] revealed that the associated haplotypes in Japanese IDDM patients were quite different from those of other populations. Such trans-racial differences are useful for determining the primary susceptibility or resistance genes to IDDM. Several studies have shown that the insulin gene region is associated with IDDM [8-lo] and thus is considered to be the second genetic factor for disease susceptibility in Caucasians. The shorter insertion (class 1 allele) in the 5’ insulin gene polymorphism is positively associated with IDDM in Caucasians. This is also true for poly-

0168-8227/94/$07.00 0 1994 EIsevier Science Ireland Ltd. AI1 rights reserved SSDI 0168-8227(94)0899-6

St34

T. Awata, Y. Kanazam~ ~&&etm

Rs. Clin. Pruct. 24 Suppl. (1994) S83-S87

morphisms linked to the class 1 allele [lo]. HOWever, this region is less polymorphic in Japanese and an association with IDDM was not observed. In this section, we summarize the data for the HLA class II genes and insulin gene for Japanese 1DDM patients. 2. U

class II genes on chromosome 6p

2.1. HLA class II alleles HLA class II (DRBl, DQAl and DQBl) alleles associated with IDDM in Japanese subjects are shown in Table 1. D-1 alleles. DRB1*0405, DRB1*0802 and DRB1*0901 (DR9) were increased, while DR2 (DRBl* 1501, DRBl* 1502) were decreased among Japanese patients. It was noted that the DRBl* 0403 and DRB1*0406 subtypes of DR4 were not increased but rather decreased in Japanese patients (6,7]. DRB1*0301 (DR3) was rare in Japanese. DQAl alleles. Consistent with the studies in Caucasians and Blacks, the DQAl*O301 allele was significantly increased among Japanese patients, and DQA1*0102 was decreased. DQAl* 0103 was also decreased. DQSl alleks. The DQBl* 0401 and DQBI* 0303 alleles were significantly increased, while DQBl* 0601 and DQBl*O602 were decreased among Japanese patients. DQBl* 0302, which was increased among Caucasians and Blacks, was increased among Japanese patients, but the magnitude of the increase was less than that observed

with DQBl* 0401 [6,7,11] and DQBl* 0303 [6,11]. DPAI and DPBl alleles. A primary association with DPAl or DPBl was not observed among Japanese IDDM patients [?,12]. DQBl position 57. More than 80% of Japanese patients [3-51 and non-diabetic subjects [3,4] had at least one DQBl allele carrying aspartic acid at position 57. This is in contrast with data from Caucasian patients where 60-100% were homozygous for non-Asp-57 alleles [l]. 2.2. DR-DQ haplotyyxs The susceptibility or resistance DR-DQ haplotypos in Japanese are shown in Table 2. DRBl* 0405-DQAl* 0301-DQBl* 0401 and DRBl* 0901-DQAl* 0301-DQBl* 0303 are the most frequently observed susceptibility haplotypes is1 Japanese, both of which are rare in Caucasians and Blacks. DRBl* 0301DQAl* 0501-DQBl* 0201 is rare in Japanese patients, but may also be a susceptibility haplotype [7], in accord with the data derived from Caucasians and Blacks. DRBl* 0405DQAl*0301-DQB1*0302, which is also rare in Japanese, seems to be associated with IDDM in Japanese [13]. We also observed that 3 of 99 IDDM patients, and none of 86 healthy subjects, had this haplotype (unpublished). This haplotype was found to be associated with IDDM in French and Algerians [l]. Further studies, however, are required to confirm these associations. In the Japanese population, DRBl* 0802-DQAl* 0301DQBl*O302 is the third most frequent suscepti-

Table 1 HL.A class II alleles associated with IDDM susceptibility or resistance in Japanese subjects [6,7,11] Susceptibility

DRBP

DQAl* DQBl*

Resistance

Allele

Relative risk

Allele

Relative risk

ON5 08Q2 0901 0301

-4 -3 l-5 6-8

0303 0401

1-5 3-4

0406 1501 1502 0102 0103 0601 0602

0.1-0.2 -0.1 0.1-0.2 o-4-0.5 0.2-0.3 0.2-0.3 -0.1

T Awatu, Y. Kanatow~

/Llinbetes Rex ch.

bility haplotype. DRBl” 0406-DQAl* OJOlDQBl* 0302 was negatively associated with IDDM in Japanese, suggesting a protective effect of DRBl* 0406 on DQAl* 0301-DQBl* 0302. A protective effect of DRB1*0403 is also possible because DRBl* 0403-DQAl* 0301-DQBl* 0302 is neutral in Japanese [6]. The DR2 haplotypes, DRBl* 1501DQAl* 0102-DQBl* 0602 and DRBl* 1502DQAl* 0103-DQBl* 0601, were both negatively associated with IDDM in Japanese. The former is also associated with resistance in Caucasians, and the similar DRBP 1503-DQAl* 0102-DQBl* 0602 is associated with resistance in Blacks, suggesting that DQA1*0102-DQB1*0602 is a primary protective molecule in all groups. The latter haplotype is rare in Caucasians and Blacks. Since DRBl* 0803-DQ!Yl* 0103-DQBP 0601 is weaklyi resistant among Japanese patients [6,7], DQAl* 0103-DQBl*O601 may be an additional protective molecule. We observed a significant decrease of DRBl* 1-DQAl* 0501-DQBl* 0301 among Japanese patients [6]. However, this was not confirmed by another study [7]. 2.3. DR-DQ genotypes The excessive risk of DR3/DR4 heterozygous individuals observed in Caucasian patients was not apparant in Japanese because the DR3 haplotype is rare. In Japanese patients, DRB1*0405DQA1*0301-DQBl”0401, DRBl*0802-

fkzct. 24 Suppi. &W4] S113-S&7

935

DQAl* 0301-DQBl* 0302 heterozygotes were excessively increased, although DRBl* 0405DQAl* 0301-DQBl* 0401, DRBl* 0901DQAP 03OlDQBl* 0303 heterozygotes were not [6,1. This increase cannot be explained by the formation of transcomplementation molecules between DQAl and DQBI, because both haplotypes carry the same DCL~~P0301 allele. 3. Insulin gene region on chromosome lip The variable number tandem repeat (VNTR), located appro-;r~t:.r_~_. :Tf:: i+, q,stream of the start of the insulin gene, is composed of tandem repeating oligonucleotides whose consensus sequence is ACAGGGGTGTGGGG. This region was classified into three classes according to length: class I, - 570 bp; class 2, - 1320 bp; class 3, es 2470 bp [S]. The class 1 alleles, which were positively associated with Caucasian IDDM, were predominant among both Japanese IDDM and non-diabetic subjects, and were not associated with diabetes (Table 3). -4pproximately 95% of Japanese individuals are homozygous for class 1 alleles. Recently, we divided the class 1 alleles into four subclasses, according to small length differences, and compared the frequencies among IDDM patients and healthy subjects [14]. This type subclass analysis did not reveal an association with IDDM. Furthermore, we found that the insulin gene po!ymorphism in the 3’ untranslated

Table 2 Probable haplotypes associated with IDDM susceptibility or resistance in Japanese subjects [6,7,13] _ Frequency DRBl-DQAl-DQBl

Relative risk

IDDM

Control

0901-0301-0303 0802-0301-0302 0405-0301-0302 0301-0501-0201

53-57% 35-52% lo-14% 3-3% O-S%

20-28% 30-33% l-3% _ 0% O--1%

3-4 l-2 4-10 6-27 1-5

Resistance 1501-0102-0602 1502-0103-0601

-1% 2-4%

0406-0301-0302

O-l%

13-22% 14-33% 5-7%

N 0.1 m-0.2 0.1-W

Susceptibility 0405-0301-0401

T. Au&a, Y:Krrrazuwa /Diebe& Res. Clin. Pratt. 24 Suppl.

s&i

(1994) S83-S87

Table 3 Genotypic and allelic frequencies at the 5’ VNTR of the insulin gene in Japanese subjects !14-181 A!Iefe

GC%lOtype l/l

l/3

3/3

Others

1

2

3

1.00 (39) 0.93 (66) 0.95 (40) 1.00 (17) 0.95 (71) 0.95 (233)

0.00 (0) 0.06 14) 0.02 (1) 0.00 (0) 0.05 (4) 0.04 (91

0.00 (0) 0.00 (01 0.00 (0) 0.00 (0) 0.00 (0) 0.!xl(0)

0.08 (0) 0.01(l) 0.02 (1) 0.08 (0) 0.08 (0) O.Ol(2)

1.09 0.96 0.98 1.00 0.97 0.98

0.00 0.01 0.01 0.09 0.08 0.01

0.09 0.03 0.01 0.00 0.03 0.02

0.95 (61) 0.94 (46) 0.97 (34) 0.95 (52) 0.94 (65) 0.95 (258)

0.05 (3) 0.04 (2) 0.03 (11 0.04 (21 0.06 (4) 0.04 (12)

0.00 (0) 0.80 (0) 0.00 (0) 0.00 (0) 0.00 (0) 0.00 (0)

0.08 (0) 0.02 (1) 0.00 (0) 0.02 (1) 0.80 (0) 0.01(2)

0.98 0.97 0.99 0.97 0.97 0.9’7

0.00 0.01 0.08 0.01 0.08 0.08

0.02 0.02 0.01 0.02 0.03 0.02

IDDM patients TOkyO

Kyoto Kobe Tochigi Aggregate Non-diabetic subjects Tokyo Kyoto Kobe To&gi Aggregate

of the insulin gene (1127/PstI), which is associated with Caucasian IDDM, was tightly linked to the 5’ VNTR, and thus was not associated with Japanese IDDM. Therefore, this region does not appear to be a valuable genetic marker for IDDM among Japanese. The high frequency of class 1 alleles in Japanese individuals dtspite the low incidence of IDDM suggests that the insulin gene region has a relatively low effect on susceptrbility to IDDM among the Japanese genetic risk factors. region

4. Other genetic markers Little is known about other genetic markers for Japanese IDDM. Recent reports [19-221 suggest a possible role of mitochondrial DNA mutations on the pathogenesis of diabetes, including IDDM. However, more studies are required to clarify this issue. It is expected that further efforts, including family studies, will elucidate other genetic markers for Japanese IDDM. References 1 Descharnps, I. and Khalii, I. (1993) The role of DQ alpha-beta heterodimers in genetic susceptibility to insuhn-dependent diabetes. Diabetes Metabol. Rev. 9, 71-92.

2 Todd, J& BeU, J.I. and McDevitt, H.O. 0987) HLADQ/3 gene contributes to suscepttbiiity and resistance to insulin-dependent diabetes mellitus. Nature 329,599-604. 3 Yamagata, K, Nakajima, H., Hanafusa T. et al. (1989) Aspartic acid at position 57 of DQP chain does not protect against type 1 (insulin-dependent) diabetes mellitus in Japanese subjects. Diabetologia 32,762-764. 4 Awata, T., Kuauya, T., Matsuda, A. et al. (1990) High frequency of aspartic acid at position 57 of I-II&DC)& chain in Japanese IDDM patients and non-diabetic subjects. Diabetes 39,266-269. 5 Ikegami, H., Tahara, Y., Cha, T. et ai. (1990) Aspartic acid at position 57 of the I-IL&DQ@ chain is not protective against insulin-dependent diabetes meliitus in Japanese people. J. Autoimmunity 3, 167-174. 6 Awata, T., Kuzuya, T., Matsuda, A., Iwamoto, Y. and Kanazawa, Y. (1992) Genetic analysii of HLA class II aileles and susceptibility to type 1 (insulin-dependent) diabetes mellitus in Japanese subjects. Diabetologia 35, 419-424. 7 Hamaguchi, K., Kimura, A., Dong, R. et al. (1992) Analysis of I-LA class II genes of Japanese type I diabetic patients by PCR-SSOP method. Molecular Diabetol. 3, 123-129 (in Japanese). 8 Bell, G.I., Ho&a, S. and Karam, J.H. (1984) A polymorphic locus near the human insulin gene is associated with insulin-dependent diabetes mellitus. Diabetes 33, 176-183. 9 Hitman, G.A., Tam, AC., Winter, R.M. et al. (1985) ‘Iype 1 (insulin-dependent) diabetes and a highly variable locus close to the insulin gene on chromosome 11. Diabetologia 28,218-222. 10 Julier, C., Hyer, R.N., Davies, J. et al. (19911Insulin-IGF2

I: Awatrr,K

155-159. 11

Ikegami, W., Kawaguc

, Y., Yamato, E. et al. 09921

h&independent dibetes Metabok 75, 1381-13&K 12 Yamagata, EL: Nanafusa, T., Nakajim& H. et al. WEW HLA-DP and susceptibility to ~u~~e~~de~t diabetes meEi&s in Japanese. Tissue Antigens 38,lOFllO. 13 Rfluniogen, KS., Spurkland, A., Tait, B. et aL 0993) class IT associations in insulin-dependent diabetes

17

18

19

ori, Y. et al. (1993) Mitochonnt @e ot diabetes

20

14 21 15 Y. and Takaku, F. (19855)Restriction polymorphism of the insulin gene regio diabetic and non-diabetic subjects. Diabetologia 28, 911-913. et al. WE%1 The 16 Takeda, J., Seine, II.,

cet 341,1291-1292 (letter). 22