COL4A1 and Gerstmann syndrome: The clinical progression to ESRD and disease prognosis in this patient with ADPKD, KS, and GS (isolated KS or GS not producing CRF) could be potentially synergistic and comparable to individuals with variants in both PKD1 and PKD2 [6,7], hypomorphic PKD1 variants and likely biallelic disease [12], the contiguous gene syndrome TSC2-PKD1 [8], co-occurrence of ADPKD and hereditary renal hypouricemia [45], or dual sequence variants in PKD2 and COL4A1 [63].