“…A total of 80 studies were included in this systematic review. Of these, 45 cohort studies were used in the meta-analytical quantitative synthesis of the frequency of PPGL among participants with vHL ( 8 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 ). On the other hand, 52 studies were used in the frequency analysis of PPGL in vHL type 2 ( 16 , 17 , 21 , 25 , 26 , 28 , 29 , 35 , 36 , 40 , 44 , 45 , 47 , 48 , 53 , 55 , 56 , 59 , 60 , 61 , …”