His sister (IV-2) developed CKD G2A2 (serum creatinine 1.0 mg/dl, cystatin C 1.75 mg/l, eGFR 62.4 ml/min/1.73 m2, protein to creatinine ratio 532 mg/g, albumin to creatinine ratio 233 mg/g) at six years of age, with hypotrophic and dysplastic kidneys on ultrasonography. Here, CST3 is linked to chronic kidney disease.