ABSTRACT
             Background and Objectives: Aging is a multi-agent phenomenon due to prolonged inflammation and stress. CD33 or Siglec3 is a membrane receptor that acts against aging by inhibiting inflammatory reactions. The aim of this study was to evaluate a possible relationship between CD33 copy number and lifespan of an Iranian population.
             Methods: The study included 50 individuals with cancer or Alzheimer's disease as the case group and 50 members of a family over 70 years old as the control group. Blood samples were collected and transferred to the laboratory. CD33 copy number was calculated using the QX100 Droplet Digital PCR system. A number of CD33 single-nucleotide polymorphisms including rs3865444, rs273634 and rs3852865 were genotyped using specific primers and the PCR method.
             Results: The mean number of CD33 copies among the case group (7.78) was significantly lower (P<0.05) than control group (12.72). In the case group, the mean number of CD33 copies was 7.83 among men and 7.73 among women. In the control group, the mean number of CD33 copies was 12.73 among men and 12.71 among women.
             Conclusion: CD33rSiglecs counteract random molecular damage, which is the main driver of aging. Therefore, the CD33rSiglec gene number may be correlated with longevity. Our results indicate that there may be a link between reduced CD33rSiglec copy number and development of diseases.
             Keywords: Gene Copy Number, Siglec-3, CD33 Antigens, Cancer.