Early onset of nephrogenic diabetes insipidus due to fabry disease in a child with N215S mutation: Case report and literature review.

BACKGROUND

Fabry disease (FD) is a rare X-linked lysosomal storage disorder. Renal involvement in FD is characterized by proteinuria and progressive renal decline. Reports on FD with nephrogenic diabetes insipidus as the initial manifestation are rare. In this paper, we report a pediatric case with an N215S variant.

RESULTS

A boy with an onset of polydipsia and polyuria at approximately 4 years of age was diagnosed with nephrogenic diabetes insipidus. Whole-exome sequencing showed a GLA N215S variation with no secondary cause of diabetes insipidus. No family history of polydipsia or polyuria was reported; however, the patient's maternal grandmother and her two younger brothers had hypertrophic cardiomyopathy. Both brothers required surgery due to severe cardiac involvement, and the youngest brother died of heart disease at the age of 50 years. The patient's polydipsia and polyuria worsened over the next 7 years. Serum sodium was normal, but the patient required high-dose potassium chloride to maintain normal serum potassium levels. His physical and intellectual development was normal, with no common complications of nephrogenic diabetes insipidus, such as anemia, malnutrition, vomiting, high fever, or convulsions. Dried blood spot testing showed α-galactosidase A (α-gal A) activity of 0.6 μmol/L/h and a Lyso-GL-3 level of 7.01 ng/ml. The patient developed mild proteinuria and mild myocardial hypertrophy. Renal biopsy showed myeloid bodies and zebra bodies. After more than 1 year of ERT, his urine specific gravity increased to 1.005-1.008, which was a new sign reflecting the efficacy of ERT, although urine output was maintained at 3-5 ml/kg/hour. We will continue to monitor the patient's renal tubular function and urine output.

CONCLUSIONS

Nephrogenic diabetes insipidus may be the initial manifestation in children with FD and/or N215S variation. In FD, the same mutation in a family may present a completely different phenotype.