Increased awareness around an ultra-rare disease can improve diagnosis delays: the French example in primary hyperoxalurias

Background Primary hyperoxalurias (PH) are rare recessive autosomal genetic diseases inducing increased hepatic oxalate production. Apart from genetic background, their prognosis depends mainly on diagnosis delay. We recently reported shorter diagnosis delay in children compared with adults (1.2 (0.1–3.0) versus 30 (17–36) years) in a French PH cohort of 52 patients diagnosed between 2015 and 2019. In 2020, the first RNA interfering therapy was approved, leading to increased awareness and communication from reference centres, scientific societies and pharmaceutical companies. Our aim was to evaluate whether diagnosis delay was improved in this global setting. Methods We performed a retrospective study including all consecutive patients that received a positive genetic test for PH in our expert genetic laboratory in Lyon between January 2020 and December 2024. We compared outcomes with the historical cohort. Diagnosis delay was defined by the time between the first symptoms and the result of genetic test. Results In total, 62 patients (37 children) were included. Forty-two (78%) patients had PH type 1, 5 (8%) had PH2 and 11 (18%) had PH3. The diagnosis delay remained significantly shorter in children as compared to adults (0.75 (1.10) versus 15 (16.21) years, p < 0.05), but decreased in both sub-groups when compared to the previous study. Conclusions The delay in PH diagnosis in France has been halved over the past five years. This improvement may be associated with recent therapeutic developments and increased awareness of the disease. Earlier diagnosis may enable earlier management, which might ultimately contribute to improved overall prognosis.