The p53 tumor suppressor protein plays an important role in cell apoptosis. The wild type p53 protein presents a common polymorphism at position 72 resulting in either a proline or an arginine residue at this position, leading to differences between the two variants in the induction of apoptosis. We examined the possible associations of this polymorphism with the occurrence of rheumatoid arthritis (RA) and its severity in a series of RA patients of Italian origin.
170 consecutive RA patients fulfilling the 1997 ACR criteria and seen over a 4-month period in our rheumatology centre were studied. The medical records of the patients were reviewed for demographic and clinical parameters. Radiographs of the hands and feet taken at disease onset and after 5 years were available for 122 of the patients and were used to determine the presence and number of erosions, which were scored according to the modified Sharp/van der Heijde method (S/vdH). All of the RA patients and controls were genotyped by the polymerase chain reaction and allele-specific oligonucleotide techniques for p53 gene polymorphism Arg/Pro at codon 72.
The distribution of the polymorphism of Arg/Pro 72 did not differ significantly between patients and healthy controls (Arg/Arg 47.1 vs 48.5%, Arg/Pro 43.5% vs 42%, Pro/Pro 9.8 vs 9.5% respectively, p=ns). Patients carrying the Pro/Pro genotype had a significantly higher percentage of erosive disease at year 5 compared with patients carrying the Arg/Arg genotype (Pro/Pro 93%, Arg/Arg 52%, p=0.0001). The mean number of eroded joints per patient at 5 years was higher in the Pro/Pro subgroup and significantly lower in the Arg/Arg subgroup (Pro/Pro 13.2, Arg/Arg 3.6, p=0.0001). The mean S/vdH erosive score, joint space narrowing score and total damage score were significantly higher in the Pro/Pro subgroup compared with the Arg/Arg and Arg/Pro subgroups.
In the Italian population there is no association between codon 72-p53 gene polymorphism and the occurrence of RA. However, this polymorphism is associated with the structural damage of the disease.