Cystinosis beyond kidneys: gastrointestinal system and muscle involvement

Cystinosis is a multisystemic disease resulting from cystine accumulation primarily in kidney and many other tissues. We intended to study the evolution of less commonly seen extrarenal complications of cystinosis in a group of patients who have periods without cysteamine treatment.

Gastrointestinal and muscular complications of cystinosis were studied in a group of 21 patients.

Twenty one patients were included in the study. Among them, 14 were homozygous and 3 were compound heterozygous for CTNS mutations. The median age of diagnosis was 15 months (range; 5 months-14 years) and the mean age at last visit was 11.3 ± 6.5 years. Nine patients (42%) had end stage renal disease at a mean age of 10.6 years (6.5-17 years). Abdominal ultrasonography and portal vein doppler ultrasonography were performed in19 patients, 14 of them (74%) had hepatomegaly, 10 patients (53%) had granular pattern or heterogeneity of liver. Only one patient had high transaminase levels and liver biopsy showed cystine crystals in the liver. Eleven patients (58%) had borderline or increased portal vein minimum and maximum flow velocities. One patient had CK level of 9024 U/L and electromyographic study showed active myopathic involvement. Two patients were found to have gastroesaphageal reflux only and 4 patients were found to have esophageal remnants in addition to reflux.

In addition to renal functions, extrarenal organs may be affected from cystine accumulation even in childhood, especially in patients who are incompliant to treatment, resulting in complications such as swallowing difficulty, hepatomegaly and portal hypertension.