TGFB1 and renal fibrosis: The author puts forward two hypotheses about the changes in renal function in this child: one possibility is that chronic stimulation of RAAS increases the response of ATII to chronic renal dysfunction caused by salt loss nephropathy; the other possibility is that long-term hypokalemia may lead to hypertrophy and renal fibrosis by activating transforming growth factor β (TGF-β), so the scholar thinks that the renal changes in this child are caused by BS (14).