E72.04

Clinical Causes: Genetic mutations: Cystinosis is caused by mutations in the CTNS gene, which encodes the lysosomal transporter protein cystinosin. Inheritance pattern: The disorder follows an autosomal recessive inheritance, meaning an affected individual inherits two copies of the mutated gene, one from each parent. Family history: A family history of cystinosis increases the likelihood of inheriting the condition. Compounded syndromes: When cystinosis occurs alongside Fanconi or Debré syndromes, overlapping genetic factors may influence disease manifestation.

Key Symptoms: Kidney issues: Progressive kidney damage, including symptoms like excessive urine production (polyuria), dehydration, and electrolyte imbalances. Eye problems: Crystal deposits in the cornea causing sensitivity to light, pain, and visual disturbances. Growth retardation: Delayed growth and development in children. Muscle weakness: Due to crystal accumulation in muscle tissues. Diabetes mellitus: As the disease progresses, pancreatic function may be affected, leading to diabetes. Digestive disturbances: Nausea, vomiting, and poor appetite in some cases. Additional symptoms if associated with Fanconi syndrome: Increased loss of sugars, amino acids, phosphate, and bicarbonate in urine resulting in metabolic acidosis and growth issues. Other possible signs include fatigue, rash, and characteristic facial features in severe cases.

Diagnosis Path: Diagnosis of cystinosis involves a combination of clinical evaluation and laboratory tests. These include measuring cystine levels in white blood cells, which are elevated in affected individuals. Slit-lamp examinations can reveal cystine crystals in the cornea. Genetic testing is used to confirm mutations in the CTNS gene. Imaging studies and kidney function tests are also performed to assess organ involvement and disease severity. Early diagnosis, especially in infants presenting with kidney symptoms, is vital to prevent irreversible damage.

Treatment Protocols: Management of cystinosis primarily focuses on reducing cystine accumulation and preventing organ damage. This involves administering cystine-depleting medications such as cysteamine, which helps to clear crystals from tissues. Supportive treatments may include kidney dialysis or transplantation in cases of severe renal failure. Regular ophthalmologic examinations and interventions are necessary for eye-related issues. Additionally, managing complications like metabolic acidosis, electrolyte imbalances, and growth delays is important. Multidisciplinary care teams, including nephrologists, ophthalmologists, and other specialists, are essential for comprehensive management of the disorder.