Variations of the perforin gene in patients with type 1 diabetes.
OBJECTIVE
Perforin plays a key role in cell-mediated cytotoxicity. Mutations of its gene, PRF1, cause familial hemophagocytic lymphohistiocytosis but have also been associated with lymphomas and the autoimmune/lymphoproliferative syndrome. The aim of this work was to investigate the role of PRF1 variations in type 1 diabetes.


METHODS
We typed for the N252S and A91V variations in an initial population of 352 type 1 diabetic patients and 816 control subjects and a second population of 365 patients and 964 control subjects. Moreover, we sequenced the coding sequence and intron-exons boundaries in 200 patients and 300 control subjects.


RESULTS
In both cohorts, allelic frequency of N252S was significantly higher in patients than in control subjects (combined cohorts: 1.5 vs. 0.4%; odds ratio 6.68 [95% CI 1.83-7.48]). Sequencing of the entire coding region detected one novel mutation in one patient, causing a P477A amino acid change not detected in 199 patients and 300 control subjects. Typing for HLA-DQA1 and DQB1 alleles showed that type 1 diabetes-predisposing DQ alpha/DQ beta heterodimers were less frequent in patients carrying N252S or P477A than in those carrying wild-type PRF1. We previously found that natural killer (NK) activity is not decreased in most N252S heterozygotes, but we detected one whose NK activity was normal at the age of 12 but strikingly low in early childhood. Here, we discovered that NK function was low in three heterozygotes in early childhood, one homozygous adult, and in the subject carrying P477A.


CONCLUSIONS
These data suggest that N252S and possibly other PRF1 variations are susceptibility factors for type 1 diabetes development.
Orilieri
Elisabetta
E
Interdisciplinary Research Center of Autoimmune Diseases and Department of Medical Sciences, A. Avogadro University of Eastern Piedmont, Novara, Italy.
Cappellano
Giuseppe
G
Clementi
Rita
R
Cometa
Angela
A
Ferretti
Massimo
M
Cerutti
Elisa
E
Cadario
Francesco
F
Martinetti
Miryam
M
Larizza
Daniela
D
Calcaterra
Valeria
V
D'Annunzio
Giuseppe
G
Lorini
Renata
R
Cerutti
Franco
F
Bruno
Graziella
G
Chiocchetti
Annalisa
A
Dianzani
Umberto
U
D000293:Adolescent; D000328:Adult; D019943:Amino Acid Substitution; D015331:Cohort Studies; D017931:DNA Primers; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics* / Q000276:immunology; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D014644:Genetic Variation; D006683:HLA-DQ Antigens / Q000235:genetics; D059848:HLA-DQ alpha-Chains; D059866:HLA-DQ beta-Chains; D006801:Humans; D007558:Italy; D008297:Male; D054353:Perforin; D020641:Polymorphism, Single Nucleotide; D052899:Pore Forming Cytotoxic Proteins / Q000235:genetics*; D012016:Reference Values
D017931:DNA Primers; D006683:HLA-DQ Antigens; D059848:HLA-DQ alpha-Chains; D059866:HLA-DQ beta-Chains; C069050:HLA-DQA1 antigen; C069051:HLA-DQB1 antigen; C510468:PRF1 protein, human; D052899:Pore Forming Cytotoxic Proteins; D054353:Perforin