Introduction: Primary hyperoxalurias (PHs) are rare disorders leading to overproduction and increased urinary excretion of oxalate. Three monogenic forms (PH1-PH3) were classified. PHs lead to urolithiasis and chronic kidney disease. There are only sparse data on patients with PH from Eastern European countries including Poland.
Objectives: The aim of the study was to evaluate the prevalence, genetic background, and clinical course of PH in the Polish population.
Patients and methods: This was a retrospective multicenter study including data of all identified and genetically confirmed Polish patients with PH.
Results: Between 1998 and 2019, 21 patients with PH were identified, including 13 patients with PH1 (62%), 2 with PH2 (9%), and 6 with PH3 (29%). In those with PH1, the most common mutation was c.508G>A in AGXT and in PH3, c.700+5G>T in HOGA1. Nine patients (69%) developed end‑stage renal disease at a median age of 13 years and 2 died. In 6 (46%) PH1 cases, the diagnosis was made only after patients had progressed to end‑stage renal disease and received isolated kidney transplantation, followed by graft failure. Combined liver‑kidney transplantation was performed in 6 patients with PH1. Two siblings with PH2 showed a milder course with slightly decreased renal function in one, at age of 11 years. Despite infantile onset of urolithiasis, all patients with PH3 at a median age of 10 years maintained normal renal function.
Conclusions: The prevalence of PH1 and PH2 in Poland seems to be much lower than in Western countries with PH3 constituting about 30% of all cases. The molecular findings and clinical course are typical, but the underdiagnosis is of concern.