title: [Cystinosis: diagnosis through the measurement of the leukocyte cystine content by HPLC].
abstract: OBJECTIVE
  Cystinosis is an autosomal recessive disorder characterized by an accumulation of intralysosomal cystine. Three disease forms exist, infantile, juvenile or late-onset, and ocular nonnephropathic cystinosis, delineated on the basis of severity of symptoms and age of onset. The knowledge of early clinic manifestations and the onset of the appropriate therapy delay the evolution of the disease and improve the general conditions. Therefore, it is necessary to develop a sensible diagnostic method for early detection and treatment of the disease. CLINICAL CASE AND METHODS: The leukocyte cystine content was determined by HPLC in a 42 years old female patient after renal transplantation, and with the clinical characteristic complications of the intermediate cystinosis. Equally, the molecular characterization of the structural defects of the cystinosin (CTNS) gene was made in the patient and in all family members.
  
  
  RESULTS
  By measuring of the leukocyte cystine content in the patient and family members, we have determined 5 family members as heterozygous. This result was confirmed by molecular analysis that showed the approximately 65 kb deletion in the 5 family members. The patient was heterozygous for the approximately 65 kb deletion, and the second alteration was not determined.
  
  
  CONCLUSIONS
  We presented a useful diagnostic method, based in the determination of cystine content of polymorphonuclear leukocytes, which permits to detect the heterozygous individuals.
authors.affiliation: Servicio de Análisis Clínicos, Hospital Universitario Virgen de las Nieves, Granada, Spain.
authors.forename: María Soledad
authors.initials: MS
authors.lastname: Martínez Llamas
authors.forename: Carmen M
authors.initials: CM
authors.lastname: Cabrera Morales
authors.forename: Juan Antonio
authors.initials: JA
authors.lastname: Bravo Soto
authors.forename: Julia
authors.initials: J
authors.lastname: Cantón
authors.forename: Susana
authors.initials: S
authors.lastname: Pedrinaci
mesh_terms: D000328:Adult; D026921:Amino Acid Transport Systems, Neutral; D002851:Chromatography, High Pressure Liquid; D003553:Cystine / Q000097:blood*; D003554:Cystinosis / Q000175:diagnosis*; D005260:Female; D006580:Genetic Carrier Screening; D006023:Glycoproteins / Q000235:genetics; D006801:Humans; D007962:Leukocytes / Q000737:chemistry*; D008565:Membrane Proteins / Q000235:genetics; D026901:Membrane Transport Proteins; D010375:Pedigree
chemical_list: D026921:Amino Acid Transport Systems, Neutral; C111445:CTNS protein, human; D006023:Glycoproteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D003553:Cystine