Eyes are a gateway to the kidney – A rare case of cystinosis

Abstract

A 6-year-old girl born through third-order consanguinity (the other two siblings girls and parents have no kidney disease). She presented with failure to thrive, polyuria, polydipsia, photophobia, poor social interaction, poor eating, and a craving for salt. On examination, growth retardation and severe malnutrition were discovered. Height for age below the third percentile, weight for age below the third percentile, severe pallor, and rickets features were also present. Anaemia, non-oliguric renal dysfunction, normal anion gap metabolic acidosis, urine anion gap positive, rickets on wrist X-ray, hypophosphatemia, hypocalcaemia, hyponatraemia, and hypokalaemia were reported. On ophthalmology examination, cystine crystals deposits in the stroma of the cornea were noted. Fundus examination showed crystalline retinal deposits. On Genetic workup, homozygous 4 base pair deletion in exon 3 of the CTNS gene (chr17: g.3640224_3640227del; Depth: 78×) that results in a frameshift and premature truncation of the protein 7 amino acids downstream to codon 7 (p.Thr7phefster7; ENST00000381870.8) was detected. Cystinosis can be diagnosed using specific symptoms, a complete clinical evaluation, a full patient history, and a range of specialist tests. To get the most out of the preventive and therapeutic effects of cystine depleting drugs, cystinosis must be diagnosed as early as possible.