Abstract A boy, aged 1 year and 6 months, was found to have persistent positive urine glucose at the age of 4 months, with polydipsia, polyuria, and growth retardation. Laboratory examinations suggested that the boy had low specific weight urine, anemia, hypokalemia, hyponatremia, hypomagnesemia, metabolic acidosis, glycosuria, acidaminuria, increased fractional excretion of potassium, and decreased tubular reabsorption of phosphate. X-ray examinations of the head, thorax, and right hand showed changes of renal rickets. The slit-lamp examination showed a large number of cystine crystals in the cornea. The genetic testing showed a suspected pathogenic homozygous mutation of the CTNS gene, C.922g>A(p.Gly308Arg). The boy was finally diagnosed with cystinosis. At the beginning of treatment, symptomatic supportive treatment was given to maintain the stability of the internal environment, and cysteamine tartaric acid capsules were used after diagnosis to remove cysteine. This article reported a case of cystinosis caused by CTNS gene mutation and summarized the etiology, clinical features, diagnosis, and treatment of this disease, which can provide a reference for the early diagnosis, treatment, and subsequent study of the disease.
Kalatzis V, Nevo N, Cherqui S, et al. Molecular pathogenesis of cystinosis: effect of CTNS mutations on the transport activity and subcellular localization of cystinosin[J]. Hum Mol Genet, 2004, 13(13): 1361-1371. PMID: 15128704. DOI: 10.1093/hmg/ddh152.
Richards S, Aziz N, Bale S, et al. Standards and guidelines for the interpretation of sequence variants: a joint consensus recommendation of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology[J]. Genet Med, 2015, 17(5): 405-424. PMID: 25741868. PMCID: PMC4544753. DOI: 10.1038/gim.2015.30.
Gaide Chevronnay HP, Janssens V, Van Der Smissen P, et al. A mouse model suggests two mechanisms for thyroid alterations in infantile cystinosis: decreased thyroglobulin synthesis due to endoplasmic reticulum stress/unfolded protein response and impaired lysosomal processing[J]. Endocrinology, 2015, 156(6): 2349-2364. PMID: 25811319. PMCID: PMC4430621. DOI: 10.1210/en.2014-1672.
