Short‐cut diagnostic tool in cystinosis: Bone marrow aspiration

Background Cystinosis is a rare metabolic genetic disorder caused by a mutation in cystinosin lysosomal cystine transporter ( CTNS ). The diagnosis of nephropathic cystinosis ( NC ) is made by observing corneal cystine crystals and/or measuring the cystine content of leukocytes. CTNS mutation analysis confirms the diagnosis of cystinosis, but leukocyte cystine measurement and CTNS analysis have not been widely available, and cystine crystals in the cornea may not be apparent in the first months of life. Cystine crystal deposition can be seen in the bone marrow earlier than corneal deposition, in patients with NC . Methods Ten patients with cystinosis diagnosis were enrolled in the study. Medical records were reviewed retrospectively to collect demographic and clinical data such as age at diagnosis, disease presentation, parental consanguinity, family history, corneal cystine deposition, leukocyte cystine level, bone marrow cystine deposition, presence of renal failure, follow‐up time and prognosis. Results Cystine crystals were seen in all of the patients’ fresh bone marrow aspiration samples. Eight patients had corneal cystine deposition. Leukocyte cystine measurement could have been performed in four patients who had come from another center. Complications such as pulmonary hypertension and idiopathic intracranial hypertension ( IIH ) were observed in two patients. Conclusions Bone marrow aspiration might be an easy and short‐cut diagnostic tool for NC especially when it is not possible to measure fibroblast cystine content. Additionally some rare complications such as pulmonary hypertension and IIH can be encountered during the course of NC .