Primary Hyperoxaluria Type 1 in Japan

Abstract

Background/Aims: Current status of primary hyperoxaluria (PH) has not been surveyed in Japan. Methods: Japanese patients with PH were reviewed in the published literature. Results: Fifty-nine patients were diagnosed as PH from 1962 to 2003. The median ages both at diagnosis and at the onset of initial symptoms were 17 (range: 0.02–63) and 13 (range: 0–58) years, respectively. Twenty-nine (49%) patients were older than 20 years at diagnosis, among whom 26 (90%) already presented end-stage renal failure (ESRF) or soon evolved into ESRF. Among 30 (51%) diagnosed as PH under 20 years old, only 13 (43%) were already in a terminal stage of renal insufficiency. Ten patients were diagnosed as PH1 by liver biopsy. We identified two types of enzymatic phenotypes in 3 of those patients examined. In 1 case, immunoreactive SPT/AGT protein level was very low due to accelerated proteolysis, while in other 2 cases, the immunoreactivity was detected on mitochondria due to mistargeting. Of 9 cases having been subjected to kidney transplantation at a median age of 20 years (range 7.3–40.0), it was only 2 cases that were reported to be successful, while the median survival time of the kidney grafts being 1.4 years (range 0–7). Of 4 patients having undergone combined liver/kidney transplantations (at the ages of 1.3, 1.4, 9 and 41 years, respectively), the surgery was successful in 3 cases; in the remaining one case, however, rejection required removal of the transplanted kidney was observed. The overall survival ratio of all the 59 PH cases accounted for 77, 71 and 55% at 5, 10 and 20 years, respectively. Conclusion: Assuming that the majority of the 59 patients with PH reported was classified as PH1, it is postulated that morbidity of violent infantile PH1 in Japan might be less than those in the USA and Europe, and symptoms of elderly Japanese PH1 patients seem to be milder than those of Western patients. Establishment of an early detection system of PH1 and more popular application of combined liver/kidney transplantation deserve further study.