The heterozygous 20210 G/A genotype prevalence in patients affected by central and branch retinal vein occlusion: a pilot study

Background: Several inherited conditions have been associated with an incre ased or decreased incidence of retinal vein occlusion (RVO). The A allele i n the 20210 G/A prothrombin gene has been found to be associated with syste mic venous thrombosis. The aim of this study has been to verify the prevale nce of this mutation in patients affected by central RVO (CRVO) or branch R VO (HRVO). Methods: A retrospective study was carried out on 100 consecutiv e patients suffering from RVO, more than 50 years old, unaffected by system ic diseases known to be associated with markedly increased RVO occurrence. We determined the frequency of this mutation by performing mutagenised ampl ification of exon 14 followed by restriction analysis of the amplified DNA fragment. Results: The overall frequency of prothrombin 20210A allele in RV O patients was 6.0%. All heterozygous patients had suffered from CRVO. In t his study subgroup, the frequency of the 20210 G/A prothrombin heterozygosi s was 12.0%. The difference in the frequency of this the genetic variant be tween the CRVO and BRVO groups was statistically significant. None of the c onventional RVO risk factors were statistically related to the occurrence o f the disease in either the CRVO or the BRVO subgroup. Conclusion The preva lence of the prothrombin 20210A mutation observed in CRVO patients is signi ficantly higher than in the normal Italian population. Moreover, the preval ence is significantly greater in CRVO than in BRVO patients. These results raise the possibility that the prothrombin 20210A variant may be considered as a risk factor for CRVO.