Background
ACP1 (acid phosphatase locus 1, a cytosolic low-molecular-weight phosphotyrosin phosphatase) and ADA1 (adenosine deaminase locus 1) are two polymorphic systems involved in immune reactions. Observed interactions at the biochemical and clinical levels between the two systems prompted this investigation of a possible interaction concerning susceptibility to type 1 diabetes.
Material and Method
Two hundred eighty-seven children admitted consecutively to the hospital for type 1 diabetes and 727 healthy newborn infants were studied. All were from the Caucasian Italian population living in the central area of Italy. ACP1 and ADA1 genotypes were determined by DNA analysis.
Results
In the type 1 diabetics the distribution of ACP1 genotypes was dependent on the ADA1 genotypes, showing an excess of the low-activity *A/*A and *A/*B genotypes in the ADA1*2 carriers compared with the ADA1*1/*1 subjects (OR: 2.200, 95%CI: 1.133-4.298). Such an association was not present in the healthy newborn infants.
Conclusions
This investigation based on the biological effects of ACP1 and ADA1 on the immune system and on the known biochemical interaction between the two systems showed a significant interaction between the two system concerning susceptibility to type 1 diabetes. The low-activity ACP1 genotypes *A/*A and *A/*B carrying the low-activity ADA1*2 allele were more common in type 1 diabetic than in healthy newborns (OR: 1.699 95%CI: 1.066-2.702).

Keywords: Protein Tyrosine Phosphatases - genetics, Polymorphism, Single Nucleotide - genetics, Infant, Newborn, Health, Genetic Predisposition to Disease, Diabetes Mellitus, Type 1 - genetics, Case-Control Studies, Proto-Oncogene Proteins - genetics, Alleles, Adenosine Deaminase - genetics