A small kidney size is one of the important characteristics of BEN, especially in advanced stages. Lezaik et al concluded that compared with other kidney diseases, BEN patients had smaller kidneys. [23] However, it is unclear when the shrinkage starts. Some studies suggest that kidney sizes are normal in patients without renal failure, but decrease remarkably as the disease progresses. [24],[25] Recent studies, conversely, have shown that a reduction in kidney length appears in the early stage. [21],[26] Our previous results found a reduction of kidney length in healthy offspring with a family history of BEN. [17],[27] In addition, smaller kidney cortex widths were identified among participants with a family history of BEN prior to disease onset. [17],[27] Maternal history of BEN was a stronger predictor of kidney size than paternal history. [17],[27]