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Corneal cystine crystals in cystinosis

21 Mar 2017

A 7-year-old girl presented with polyuria and developmental delay. She had previously been diagnosed with secondary Fanconi syndrome and cystinosis, at the age of 4 years, but her parents did not comply with cysteamine treatment. Physical examination revealed severe growth failure and genu valgum. Venous blood gas analysis indicated metabolic acidosis. Urine analysis indicated glucosuria and proteinuria, with a urine pH of 5.5. Slit-lamp examination showed moderate corneal oedema and multiple crystal deposits in both eyes (figure 1). The diagnosis was confirmed by analysis of the CTNS gene, which revealed homozygous mutations in c.681 G>A (p.E227E).

Cystinosis is a rare autosomal recessive lysosomal disorder caused by mutations in the CTNS gene. It can be divided into three types: nephropathic infantile form, nephropathic juvenile form and ocular form. Ninety-five per cent of patients with cystinosis have the nephropathic infantile form, with renal Fanconi syndrome, poor growth, rickets and progressive renal damage.

Click here to view the full article which appeared in Archives of Disease in Childhood