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Diagnostic challenge in a patient with nephropathic juvenile cystinosis: a case report.
- Source :
-
BMC nephrology [BMC Nephrol] 2017 Sep 26; Vol. 18 (1), pp. 300. Date of Electronic Publication: 2017 Sep 26. - Publication Year :
- 2017
-
Abstract
- Background: Cystinosis is a rare autosomal recessive lysosomal disorder characterized by the accumulation of cystine in lysosomes. Cystinosis is much rarer in Asian than Caucasian populations. There are only 14 patients have with cystinosis alive in Japan. Most cystinosis is the nephropathic infantile form, as indicated by its apparent and severe clinical manifestations, including renal and ocular symptoms. Patients with the nephropathic juvenile form account for 5% of those with cystinosis. Their diagnosis is frequently delayed and difficult because of slower progression to end-stage renal disease and fewer cystine crystals in the cornea. Molecular analysis and a cysteine-binding protein assay should be performed when patients with proximal tubulopathy of an unknown origin are encountered.<br />Case Presentation: A 12-year-old boy had been suffering from Fanconi syndrome since he was 3 years old. He was only recently diagnosed despite repeated ophthalmological examinations. Corneal cystine crystals were found when he was 12 years old, and he was diagnosed with cystinosis by high free cystine content in granulocytes (6.36 nmol half-cystine/mg protein, normal: <0.15). Analysis of the CTNS gene showed two novel heterozygous single nucleotide substitutions of c.329G > C and c.329 + 2 T > C. Both were splicing site variants causing exon 6 skipping proven by transcript analysis, although the functional prediction site showed c.329G > C, p.(Gly110Ala) as a benign missense substitution. The patient's estimated glomerular filtration rate was 66.8 mL/min/1.73 m <superscript>2</superscript> . He was immediately treated with cysteamine after diagnosis.<br />Conclusions: Even if no ophthalmological abnormalities are present, nephropathic juvenile cystinosis should be suspected in children with Fanconi syndrome. Transcript analysis was useful to detect pathogenic splicing variants in this patient.
- Subjects :
- Child
Cysteamine therapeutic use
Cystinosis drug therapy
Fanconi Syndrome drug therapy
Humans
Male
Nephrotic Syndrome drug therapy
Slit Lamp Microscopy methods
Cystinosis diagnosis
Cystinosis genetics
Fanconi Syndrome diagnosis
Fanconi Syndrome genetics
Nephrotic Syndrome diagnosis
Nephrotic Syndrome genetics
Subjects
Details
- Language :
- English
- ISSN :
- 1471-2369
- Volume :
- 18
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- BMC nephrology
- Publication Type :
- Academic Journal
- Accession number :
- 28950840
- Full Text :
- https://doi.org/10.1186/s12882-017-0721-4