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Journal of Diabetes 7 (2015) 430–432
RESEARCH LETTER
Genetic factors adaptive in a malarial environment may increase the risk of type 1 diabetes Fulvia GLORIA-BOTTINI and Egidio BOTTINI Department of Biomedicine and Prevention, University of Rome Tor Vergata, School of Medicine, Rome, Italy
Keywords: adenosine deaminase, malaria, P53 codon 72, type 1 diabetes.
Common disease of modern populations could be connected with past selection of genetic polymorphisms involved in adaptation to malaria endemia. The discovery of genes responsible for susceptibility to these diseases and for resistance to malaria may give some hints about the underlying mechanism of apparently unrelated diseases. Herein we consider two genetic systems involved in immune functions and compare genetic differences between the lowlands of Sardinia, characterized by heavy malarial endemia (Oristano area; altitude 9 m above sea level (a.s.l.); past malaria endemia 95%), and the highlands of Sardinia, characterized by low malarial endemia (Nuoro area; altitude 900 m a.s.l.; past malaria endemia 12%), as well as between individuals with type 1 diabetes (T1D) and a controls group. The original data have been reported previously,1–4 separately for T1D and for past malarial endemia in Sardinia. Herein we show that genes connected with resistance to malaria are also involved to susceptibility to T1D. The Adenosine Deaminase locus 2 (ADA2) genotype was determined in 184 children with T1D and 240 controls,2 as well as in 51 newborns from Oristano and 48 newborns from Nuoro.3 In addition, p53 codon 72 genotypes were determined in 281 children with T1D and 730 controls,3 as well as in 46 newborns from Oristano and 47 newborns from Nuoro.4 The ADA2 and p53 codon 72 genotypes were determined by DNA analysis, as described previously.2,3 Statistical analyses were performed using SPSS version 19 (SPSS, Chicago, IL, USA). Correspondence Fulvia Gloria-Bottini, Department of Biomedicine and Prevention, University of Rome Tor Vergata, Via Montpellier 1, 00133 Rome, Italy. Tel.: +39 6 30889514 Fax: +39 6 72596028 Email: [email protected] Received 30 September 2014revised 10 November 2014; accepted 23 November 2014. doi: 10.1111/1753-0407.12250
430
In T1D children, mean (± SEM) blood glucose at diagnosis was 410 ± 19 mg/dL and mean (± SEM) age was 8.7 ± 0.3 years. Differences in the number of ADA2*2 allele carriers in T1D children versus controls and in the lowlands versus highlands of Sardinia are summarized in Table 1. In Oristano, an area of heavy past malarial endemia, ADA2*2 carriers were more frequent than in Nuoro, an area of low malarial endemia, suggesting a positive selection for the ADA2*2 allele in a malarial environment. Conversely, there was a higher proportion of ADA2*2 carriers in the T1D versus control group, suggesting that the ADA2*2 allele predisposes to T1D. Table 2 summarizes differences in the proportion of the *Arg/*Arg genotype in T1D versus controls and lowlands versus highlands of Sardinia. In Oristano, the *Arg/*Arg genotype is more frequent than in Nuoro, suggesting a positive selection of the *Arg allele in a malarial environment. Conversely, there was a higher proportion of carriers of the *Arg/*Arg genotype in the T1D versus control group, suggesting that the *Arg allele predisposes to T1D. As expected, in the Oristano area the incidence of T1D is higher than in other regions in Sardinia.5 The p53 codon 72 is characterized by a polymorphism in exon 4 with CGC to CCC transition (rs1042522), which confers a change of arginine to proline in the amino acid sequence of the protein. Changes in the amino acids affect the biochemical and functional properties of the p53 protein: the arginine variant is a stronger inducer of apoptosis, whereas the proline variant is a stronger transcriptional activator. Because apoptosis of liver cells seems to have a protective effect against malaria,6 one would expect a positive selection for the *Arg allele in areas of heavy malaria endemia. Conversely, p53 pathways are upregulated in T1D and there is an increased susceptibility to apoptosis.7 Thus, as expected, we found an increase in the *Arg/*Arg genotype in T1D versus control subjects.3 Adenosine deaminase (ADA) catalyses the irreversible deamination of adenosine to inosine and contributes to
© 2014 Ruijin Hospital, Shanghai Jiaotong University School of Medicine and Wiley Publishing Asia Pty Ltd
Research Letter Table 1 Distribution of ADA2 genetic polymorphisms in type 1 diabetic versus control subjects and in the lowlands (Oristano; high malarial endemia) versus highlands (Nuoro; low malarial endemia) of Sardinia1,3 T1D
Sardinia
ADA2*2 carriers T1D 51.1% Control 42.5% χ2 test of independence χ2 d.f. P-value OR (95% CI)
Total no. of subjects 184 240
Oristano Nuoro
ADA2*2 carriers
Total no. newborns
58.8% 37.5%
51 48
7.590 1 0.007 1.732 (1.152–2.603)
4.520 1 0.040 2.381 (0.984–5.806)
T1D, type 1 diabetes; OR, odds ratio; CI, confidence interval.
Table 2 Distribution of p53 codon 72 polymorphisms in type 1 diabetic versus control subjects and in the lowlands (Oristano; high malarial endemia) versus highlands (Nuoro; low malarial endemia) of Sardinia2,4 T1D
Sardinia
*Arg/*Arg genotype T1D 58.0% Controls 48.8% χ2 test of independence 6.569 χ2 d.f. P-value OR (95% CI)
Total no. of subjects 281 730
Oristano Nuoro
*Arg/*Arg genotype
Total no. newborns
67.4% 44.7%
46 47
4.541 1 0.010 1.451 (1.089–1.935)
1 0.033 2.741 (1.075–7.072)
T1D, type 1 diabetes; OR, odds ratio; CI, confidence interval.
the regulation of intra- and extracellular levels of adenosine, an autacoid mediator of adenosine receptors and lymphocyte function. Adenosine deaminase is present on the surface of lymphocytes, where it acts as ectoenzyme and also has a role in the maturation of the immune system during ontogenesis.8 Previous studies9 have shown that, in Sardinia, allele *2 of ADA locus 1 (ADA1) has a lower frequency in areas of heavy past malarial morbidity. More recently, it has been shown that the ADA locus is composed of 12 exons. Several single nucleotide polymorphisms (SNPs) have been discovered10,11 and we observed that the ADA2 locus is associated with both T1D and past malarial morbidity in Sardinia.2,4 Polymorphisms of the ADA2 locus can be genotyped according to the presence or absence of the Pst1 site (nucleotides 19 465–19 470, intron 2).2 The data reported herein support the hypothesis that genes involved in resistance to malaria could increase susceptibility to T1D in modern populations. One limitation of the studies is that there were only a small number of newborns evaluated in the Nuoro and Oristano areas.
Disclosure None declared.
References 1. Saccucci P, Meloni GF, Verrotti A et al. A study of three polymorphic sites of the ADA gene in children with type 1 diabetes mellitus. J Pediatr Endocrinol Metab. 2010; 23: 283–90. 2. Manca Bitti ML, Saccucci P, Bottini E, Gloria-Bottini F. p53 codon 72 polymorphism and type 1 diabetes mellitus. J Pediatr Endocrinol Metab. 2010; 23: 291–2. 3. Gloria-Bottini F, Saccucci P, Meloni GF, Bottini E. Further observations on the association between ADA gene and past malarial morbidity in Sardinia. Am J Hum Biol. 2014; 26: 716–18. 4. Gloria-Bottini F, Meloni GF, Saccucci P, Bottini E. p53 codon 72 and past malaria morbidity in Sardinia. Malar Chemother Control Elimination. 2013; 2: 1. 5. Songini M, Bernardinelli L, Clayton D et al. The Sardinian IDDM study: 1. Epidemiology and geographical distribution of IDDM in Sardinia during 1989 to 1994. Diabetologia. 1998; 41: 221–7.
© 2014 Ruijin Hospital, Shanghai Jiaotong University School of Medicine and Wiley Publishing Asia Pty Ltd
431
Research Letter
6. Leiriao P, Mota MM, Rodriguez A. Apoptotic Plasmodium-infected hepatocytes provide antigens to liver dendritic cells. J Infect Dis. 2005; 191: 1576–81. 7. Jailwala P, Waukau J, Glisic S et al. Apoptosis of CD4+ CD25(high) T cells in type 1 diabetes may be partially mediated by IL-2 deprivation. PLoS ONE. 2009; 4: e6527. 8. Franco R, Casadó V, Ciruela F et al. Cell surface adenosine deaminase: Much more than an ectoenzyme. Prog Neurobiol. 1997; 52: 283–94.
432
9. Lucarelli P, Agostino R, Palmarino R, Bottini E. Adenosine deaminase polymorphism in Sardinia. Humangenetik. 1971; 14: 1–5. 10. Viginton DA, Kaplan DJ, States JC et al. Complete sequence and structure of the gene for human adenosine deaminase. Biochemisty. 1986; 25: 8234–44. 11. Tzall S, Ellenbogen A, Eng F, Hirschhorn R. Identification and characterization of nine RFLPs at adenosine deaminase (ADA) locus. Am J Hum Genet. 1989; 44: 864–75.
© 2014 Ruijin Hospital, Shanghai Jiaotong University School of Medicine and Wiley Publishing Asia Pty Ltd
Journal of Diabetes 7 (2015) 430–432
RESEARCH LETTER
Genetic factors adaptive in a malarial environment may increase the risk of type 1 diabetes Fulvia GLORIA-BOTTINI and Egidio BOTTINI Department of Biomedicine and Prevention, University of Rome Tor Vergata, School of Medicine, Rome, Italy
Keywords: adenosine deaminase, malaria, P53 codon 72, type 1 diabetes.
Common disease of modern populations could be connected with past selection of genetic polymorphisms involved in adaptation to malaria endemia. The discovery of genes responsible for susceptibility to these diseases and for resistance to malaria may give some hints about the underlying mechanism of apparently unrelated diseases. Herein we consider two genetic systems involved in immune functions and compare genetic differences between the lowlands of Sardinia, characterized by heavy malarial endemia (Oristano area; altitude 9 m above sea level (a.s.l.); past malaria endemia 95%), and the highlands of Sardinia, characterized by low malarial endemia (Nuoro area; altitude 900 m a.s.l.; past malaria endemia 12%), as well as between individuals with type 1 diabetes (T1D) and a controls group. The original data have been reported previously,1–4 separately for T1D and for past malarial endemia in Sardinia. Herein we show that genes connected with resistance to malaria are also involved to susceptibility to T1D. The Adenosine Deaminase locus 2 (ADA2) genotype was determined in 184 children with T1D and 240 controls,2 as well as in 51 newborns from Oristano and 48 newborns from Nuoro.3 In addition, p53 codon 72 genotypes were determined in 281 children with T1D and 730 controls,3 as well as in 46 newborns from Oristano and 47 newborns from Nuoro.4 The ADA2 and p53 codon 72 genotypes were determined by DNA analysis, as described previously.2,3 Statistical analyses were performed using SPSS version 19 (SPSS, Chicago, IL, USA). Correspondence Fulvia Gloria-Bottini, Department of Biomedicine and Prevention, University of Rome Tor Vergata, Via Montpellier 1, 00133 Rome, Italy. Tel.: +39 6 30889514 Fax: +39 6 72596028 Email: [email protected] Received 30 September 2014revised 10 November 2014; accepted 23 November 2014. doi: 10.1111/1753-0407.12250
430
In T1D children, mean (± SEM) blood glucose at diagnosis was 410 ± 19 mg/dL and mean (± SEM) age was 8.7 ± 0.3 years. Differences in the number of ADA2*2 allele carriers in T1D children versus controls and in the lowlands versus highlands of Sardinia are summarized in Table 1. In Oristano, an area of heavy past malarial endemia, ADA2*2 carriers were more frequent than in Nuoro, an area of low malarial endemia, suggesting a positive selection for the ADA2*2 allele in a malarial environment. Conversely, there was a higher proportion of ADA2*2 carriers in the T1D versus control group, suggesting that the ADA2*2 allele predisposes to T1D. Table 2 summarizes differences in the proportion of the *Arg/*Arg genotype in T1D versus controls and lowlands versus highlands of Sardinia. In Oristano, the *Arg/*Arg genotype is more frequent than in Nuoro, suggesting a positive selection of the *Arg allele in a malarial environment. Conversely, there was a higher proportion of carriers of the *Arg/*Arg genotype in the T1D versus control group, suggesting that the *Arg allele predisposes to T1D. As expected, in the Oristano area the incidence of T1D is higher than in other regions in Sardinia.5 The p53 codon 72 is characterized by a polymorphism in exon 4 with CGC to CCC transition (rs1042522), which confers a change of arginine to proline in the amino acid sequence of the protein. Changes in the amino acids affect the biochemical and functional properties of the p53 protein: the arginine variant is a stronger inducer of apoptosis, whereas the proline variant is a stronger transcriptional activator. Because apoptosis of liver cells seems to have a protective effect against malaria,6 one would expect a positive selection for the *Arg allele in areas of heavy malaria endemia. Conversely, p53 pathways are upregulated in T1D and there is an increased susceptibility to apoptosis.7 Thus, as expected, we found an increase in the *Arg/*Arg genotype in T1D versus control subjects.3 Adenosine deaminase (ADA) catalyses the irreversible deamination of adenosine to inosine and contributes to
© 2014 Ruijin Hospital, Shanghai Jiaotong University School of Medicine and Wiley Publishing Asia Pty Ltd
Research Letter Table 1 Distribution of ADA2 genetic polymorphisms in type 1 diabetic versus control subjects and in the lowlands (Oristano; high malarial endemia) versus highlands (Nuoro; low malarial endemia) of Sardinia1,3 T1D
Sardinia
ADA2*2 carriers T1D 51.1% Control 42.5% χ2 test of independence χ2 d.f. P-value OR (95% CI)
Total no. of subjects 184 240
Oristano Nuoro
ADA2*2 carriers
Total no. newborns
58.8% 37.5%
51 48
7.590 1 0.007 1.732 (1.152–2.603)
4.520 1 0.040 2.381 (0.984–5.806)
T1D, type 1 diabetes; OR, odds ratio; CI, confidence interval.
Table 2 Distribution of p53 codon 72 polymorphisms in type 1 diabetic versus control subjects and in the lowlands (Oristano; high malarial endemia) versus highlands (Nuoro; low malarial endemia) of Sardinia2,4 T1D
Sardinia
*Arg/*Arg genotype T1D 58.0% Controls 48.8% χ2 test of independence 6.569 χ2 d.f. P-value OR (95% CI)
Total no. of subjects 281 730
Oristano Nuoro
*Arg/*Arg genotype
Total no. newborns
67.4% 44.7%
46 47
4.541 1 0.010 1.451 (1.089–1.935)
1 0.033 2.741 (1.075–7.072)
T1D, type 1 diabetes; OR, odds ratio; CI, confidence interval.
the regulation of intra- and extracellular levels of adenosine, an autacoid mediator of adenosine receptors and lymphocyte function. Adenosine deaminase is present on the surface of lymphocytes, where it acts as ectoenzyme and also has a role in the maturation of the immune system during ontogenesis.8 Previous studies9 have shown that, in Sardinia, allele *2 of ADA locus 1 (ADA1) has a lower frequency in areas of heavy past malarial morbidity. More recently, it has been shown that the ADA locus is composed of 12 exons. Several single nucleotide polymorphisms (SNPs) have been discovered10,11 and we observed that the ADA2 locus is associated with both T1D and past malarial morbidity in Sardinia.2,4 Polymorphisms of the ADA2 locus can be genotyped according to the presence or absence of the Pst1 site (nucleotides 19 465–19 470, intron 2).2 The data reported herein support the hypothesis that genes involved in resistance to malaria could increase susceptibility to T1D in modern populations. One limitation of the studies is that there were only a small number of newborns evaluated in the Nuoro and Oristano areas.
Disclosure None declared.
References 1. Saccucci P, Meloni GF, Verrotti A et al. A study of three polymorphic sites of the ADA gene in children with type 1 diabetes mellitus. J Pediatr Endocrinol Metab. 2010; 23: 283–90. 2. Manca Bitti ML, Saccucci P, Bottini E, Gloria-Bottini F. p53 codon 72 polymorphism and type 1 diabetes mellitus. J Pediatr Endocrinol Metab. 2010; 23: 291–2. 3. Gloria-Bottini F, Saccucci P, Meloni GF, Bottini E. Further observations on the association between ADA gene and past malarial morbidity in Sardinia. Am J Hum Biol. 2014; 26: 716–18. 4. Gloria-Bottini F, Meloni GF, Saccucci P, Bottini E. p53 codon 72 and past malaria morbidity in Sardinia. Malar Chemother Control Elimination. 2013; 2: 1. 5. Songini M, Bernardinelli L, Clayton D et al. The Sardinian IDDM study: 1. Epidemiology and geographical distribution of IDDM in Sardinia during 1989 to 1994. Diabetologia. 1998; 41: 221–7.
© 2014 Ruijin Hospital, Shanghai Jiaotong University School of Medicine and Wiley Publishing Asia Pty Ltd
431
Research Letter
6. Leiriao P, Mota MM, Rodriguez A. Apoptotic Plasmodium-infected hepatocytes provide antigens to liver dendritic cells. J Infect Dis. 2005; 191: 1576–81. 7. Jailwala P, Waukau J, Glisic S et al. Apoptosis of CD4+ CD25(high) T cells in type 1 diabetes may be partially mediated by IL-2 deprivation. PLoS ONE. 2009; 4: e6527. 8. Franco R, Casadó V, Ciruela F et al. Cell surface adenosine deaminase: Much more than an ectoenzyme. Prog Neurobiol. 1997; 52: 283–94.
432
9. Lucarelli P, Agostino R, Palmarino R, Bottini E. Adenosine deaminase polymorphism in Sardinia. Humangenetik. 1971; 14: 1–5. 10. Viginton DA, Kaplan DJ, States JC et al. Complete sequence and structure of the gene for human adenosine deaminase. Biochemisty. 1986; 25: 8234–44. 11. Tzall S, Ellenbogen A, Eng F, Hirschhorn R. Identification and characterization of nine RFLPs at adenosine deaminase (ADA) locus. Am J Hum Genet. 1989; 44: 864–75.
© 2014 Ruijin Hospital, Shanghai Jiaotong University School of Medicine and Wiley Publishing Asia Pty Ltd
