Although the association of normotensive rapid renal failure and MPO-ANCA that suggested the existence of a renal specific subset apart from scleroderma renal crisis was noted [13], nearly one-third of the MPA patients with renal involvement were hypertensive [4, 19], and hypertension was not an essential concomitant of renal failure due to SSc even though renal arterial stenosis was observed pathologically in SSc [22]. This evidence concerns the gene MPO and microscopic polyangiitis.