In treatment-naïve FD patients, we found three different groups: (i) those with C5a values ≤20 ng/ml (n=6 (25%)); (ii) between 21 - 35 ng/ml (n=11 (46%)), and (iii) > 35 ng/ml (n=7 (29%)). Here, C5 is linked to Fabry disease.