No significant differences in frequencies of the L-allele in the HMOX1 gene (associated with lower enzyme activity) between the FD and control groups were found (OR = 1.69; 95% CI = 0.54–5.24, p = 0.46) indicating no modifying role of HMOX1 promoter gene variation in FD manifestation (Table 4). The gene discussed is HMOX1; the disease is Fabry disease.