POS-432 PRIMARY HYPEROXALURIA, A TOO OFTEN MISSED DIAGNOSIS AND CAUSE OF END STAGE KIDNEY DISEASE IN ADULTS : A MONOCENTRIC TUNISIAN STUDY

Abstract

Primary hyperoxaluria (PH) is a rare hereditary metabolic disorder of oxalate overproduction. Persistently high plasma oxalate concentrations lead to potential life-threatening complications. The major objective of this study is to investigate this condition which is frequent in our country but under diagnosed. In a retrospective descriptive study, we reviewed the record of 9 patients who were diagnosed with primary hyperoxaluria hospitalized at a nephrology department during the period 2001-2020. Their demographics, clinical and investigations parameters were documented. Nine patients were enrolled and followed up. Mean age of patients was 21, 2 ± 12, 3 years with predominance of male (88, 8%). Consanguinity was noted in 28, 5%. All our patients were from Tunisian center (55, 5% were from Gafsa). Renal colic and urolithiasis were the most common symptoms in our study (100%). Ultrasonography and CT scans showed nephrocalcinosis in 5 cases (55, 55%). Urinary tract infections were observed in 2 cases (22, 2%). Renal failure was noted in almost all cases; serum creatinine level ranged from 144 to 986 µmol/L. Seven patients reached end-stage renal disease and were treated with hemodialysis at a median age of 23 years. The extra renal manifestations were bone impairment (4 cases), bone marrow fibrosis (2 cases), cardiac dysfunction (1case), digestive wall calcifications (1 case) and adrenal insufficiency (1 case). The diagnosis was based on Hyperoxaluria (1 case), positive crystalluria (1 case), kidney stone analysis (2 cases) and oxalate crystal deposition identified in both renal and bone marrow biopsy respectively in one and four cases. Mutational analysis of AGXT gene was carried out in five out of nine patients. We identified a novel frameshift mutation in the AGXT gene, the c.406_410dupACTGC resulting in a truncated protein (p.Gln137Hisfs*19). It was found in homozygous state in two related patients from the Tunisian center. Primary hyperoxaluria is not rare in the Tunisian population. In our study it was lately diagnosed in most cases. Awareness campaign to change attitude of family members to screening should be conducted.