Childhood Kidney Diseases

Korean Society of Pediatric Nephrology (대한소아신장학회)
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Early genetic diagnosis of cystinosis before corneal crystal deposition: two case reports from South India

  • Lubna K. P. (Department of Pediatrics, Aster Malabar Institute of Medical Sciences (Aster MIMS)) ;
  • Rehna K. Rahman (Department of Pediatrics, Aster Malabar Institute of Medical Sciences (Aster MIMS)) ;
  • Preetha Remesh (Department of Pediatrics, Aster Malabar Institute of Medical Sciences (Aster MIMS)) ;
  • Manjula Anand (Department of Pediatrics, Aster Malabar Institute of Medical Sciences (Aster MIMS)) ;
  • Nirmal Jayadevan (Department of Ophthalmology, Aster Malabar Institute of Medical Sciences (Aster MIMS)) ;
  • Divya Pachat (Department of Medical Genetics, Aster Malabar Institute of Medical Sciences (Aster MIMS))
  • Received : 2025.09.30
  • Accepted : 2026.02.03
  • Published : 2026.02.28
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Abstract

Cystinosis is a rare autosomal recessive lysosomal storage disorder with an incidence of approximately 1 in 100,000 to 200,000 live births. It is the most common cause of inherited pediatric Fanconi syndrome (FS). Here, we describe the cases of two infants from unrelated families who presented with polyuria and features of proximal renal tubular dysfunction. Although no corneal cystine deposition was observed at presentation, clinical suspicion and genetic analysis confirmed the diagnosis of nephropathic cystinosis. Both patients carried the same pathogenic variant in the CTNS gene, suggesting that it is a hotspot in this region. These patients were managed with oral cysteamine therapy, cysteamine eye drops, and supportive therapy for FS and are currently doing well. Genetic diagnosis plays a crucial role in the early detection of cystinosis, facilitating timely initiation of cysteamine therapy, and should be considered in infants with FS.

Keywords

Acknowledgement

We would like to thank Dr. Sujith V Nayanar, Consultant, Department of Ophthalmology.

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