Abstract: PUB209
Case Report of Imerslund-Gräsbeck Syndrome with Isolated Proteinuria as the First Clinical Sign
Session Information
Category: Pediatric Nephrology
- 1800 Pediatric Nephrology
Author
- Liu, Yuxiang, Fifth Hospital of Shanxi Medical University, Taiyuan, Shanxi, China
Introduction
We report a 10-year-old Han Chinese boy with isolated proteinuria as the sole initial manifestation, finally diagnosed with type 1 Imerslund-Gräsbeck syndrome, a rare autosomal recessive disorder, which is the first reported case in Shanxi Province, China.
Case Description
The patient was found to have proteinuria during a school physical examination, with no haematuria, oedema, hypertension, anaemia or other abnormal symptoms. Conventional treatments including benazepril and glucocorticoids yielded no improvement. Renal biopsy revealed mild glomerular lesions with only IgM positivity on immunofluorescence. Whole exome sequencing identified a homozygous CUBN gene variant c.5302_5304delATC, with both phenotypically normal parents being heterozygous carriers. His serum vitamin B12 and folic acid levels were within normal ranges, excluding the typical megaloblastic anaemia of IGS.
Discussion
IGS is caused by mutations in CUBN or AMN, which encode the cubam receptor that mediates intestinal vitamin B12 absorption and renal tubular protein reabsorption. The CUBN mutation impairs renal endocytosis, leading to isolated proteinuria without vitamin B12 deficiency. This case highlights that rare diseases should be considered in the differential diagnosis of unexplained proteinuria, and genetic testing is the key to confirm the diagnosis of IGS.
Acknowledgment
Jinyu Testing provided the renal puncture histology results, and Beijing Quanpu Medical Laboratory provided the exome sequencing results. Approved by the Ethics Committee of Shanxi Provincial People’s Hospital, No. 2024SYKLSZ-834.
Biochemical
Renal pathology