Low birthweight and premature birth are risk factors for podocytopenia and focal segmental glomerulosclerosis.

term, with an average gestational age of 25.8 weeks. The number of podocytes per glomerulus in the LBW-FSGS pa- tients was 34 and 24% lower as compared to that in the MCNS patients (p < 0.01) and the NBW-FSGS patients (p < 0.05), respectively. Similar results were observed for the WT1-positive glomerular cell number. Conclusion: LBW and premature birth were associated with FSGS development. The possibility that LBW and premature birth may be predis- posing factors for severe podocytopenia in children with FSGS warrants further investigation. Abstract Background: Recent reports suggest that low birthweight (LBW) is a risk factor for kidney diseases, including focal seg- mental glomerulosclerosis (FSGS), although the underlying pathological mechanism remains unknown. Podocyte loss triggers glomerulosclerosis; however, whether FSGS in LBW children is associated with podocytopenia is unclear. Meth- ods: We reviewed the birthweights and gestational age of all patients who underwent renal biopsies from 1995 to 2011 at our Institute. Sixteen patients had FSGS, of which 6 (37.5%) had LBW; this LBW rate was significantly higher than the overall LBW rate in Japan (9.7%). The incidence of LBW was also high in patients with minimal change nephrotic syn- drome (MCNS; 12.5%). The glomerular cell numbers in bi- opsy sections were calculated using computer image analy- sis and compared with FSGS of normal birthweight (NBW- FSGS). Biopsy specimens from age-matched patients with MCNS were also compared. Wilms' tumor-1 (WT1) immuno- histochemistry was performed to enumerate the podocytes. Results: All patients in the LBW-FSGS group were also pre-