Alpha-1-antitrypsin types and rheumatoid arthritis

Area of Science:

• Immunogenetics
• Rheumatology
• Human Genetics

Background:

• Rheumatoid arthritis (RA) is a chronic autoimmune disease with complex etiology.
• Alpha-1-antitrypsin (Pi) phenotypes are genetically determined and have been investigated for associations with various diseases.
• Previous studies on Pi phenotypes and RA have yielded inconsistent results.

Purpose of the Study:

• To investigate the frequencies of alpha-1-antitrypsin (Pi) phenotypes in Swedish patients with classical rheumatoid arthritis.
• To compare these frequencies with general population data.
• To determine if specific Pi alleles are associated with rheumatoid arthritis.

Main Methods:

• Phenotyping of alpha-1-antitrypsin (Pi) was performed on 100 female and 100 male Swedish patients diagnosed with classical rheumatoid arthritis.
• Pi phenotype frequencies in the patient cohort were statistically compared against established population frequencies.

Main Results:

• A statistically significant increase in rare Pi types (MS, MZ, MF, SZ) was observed in rheumatoid arthritis patients compared to the general population.
• The elevated frequency of rare Pi types was primarily driven by an increase in Z heterozygotes.
• This association with Z heterozygotes was more pronounced in male rheumatoid arthritis patients.
• No significant association was found between M-subtype Pi phenotypes and rheumatoid arthritis.

Conclusions:

• The study suggests a likely association between the alpha-1-antitrypsin Z allele and rheumatoid arthritis.
• The genetic link appears stronger in male patients.
• Evidence for associations between other Pi alleles and rheumatoid arthritis remains less conclusive, warranting further investigation.