Cystinuria (OMIM 220100) is a rare autosomal recessive disorder characterized by a defective reabsorption of cystine and dibasic amino acids ornithine, lysine and arginine (COLA) in the renal proximal tubule and in the epithelial cells of the gastrointestinal tract. Two genes responsible for cystinuria have been identified: SLC3A1 (2p21) which encodes the heavy subunit (rBAT) and SLC7A9 (19q12) that encodes the light subunit (b0,+AT). Type A and type B cystinuria are respectively associated with mutations in the genes SLC3A1 and SLC7A9. High cystine excretion leads to crystal precipitation in the distal tubule and forms cystine stones due to its low solubility at normal urinary pH. Cystine stones are the only manifestation of the disease.
The overall prevalence of cystinuria is 1 per 7000 with high geographic variation. Two large studies showed that cystinuria causes 1% of all cases of urolithiasis and 4-5 % of urolithiasis in children. Cystinuria is thus the most frequent renal lithiasis of genetic origin.
Currently, there is no European prospective registry for cystinuria and the published data of cystinuric patients are limited. The French Cystinuria Group in collaboration with the European Rare Kidney Disease Reference Network (ERKnet), eUROGEN, the European Society of Pediatric Nephrology and the ERA-EDTA Working Group of Inherited Kidney Diseases propose to create an European registry “EUROCYS” providing access to consistent and comparative data between centers and a continuous follow-up for this rare disease.
The objective of EUROCYS registry is to collect consistent and comparative prospective clinical, biological, genetic and radiological data from patients (children and adults) with cystinuria and followed in European centers.
EUROCYS is a multidisciplinary, European, multicenter and prospective cohort of patients with cystinuria. It includes demographic, clinical, surgical, biological, genetic, radiological and therapeutic data. These data will be recorded via ERKReg Core Registry. All Patient data are kept in the secure patient-system environment of the center where the data is collected and are handled anonymously and confidentially in ERKNet registry according to the European general data protection regulation. In each center, the data are coded with a unique patient code.
The general basic data includes:
- The common data set to ERKNet registry (Informed consent, sex, date of birth, and diagnosis data)
- Family history of cystinuria
- Additional biochemical and clinical data specific to cystinuria
- Comorbidity (Diabete and high blood pressure) data.
It includes the medication, start date, dose, route and stop date.
- Extracorporal therapies
- Type of therapy
- Start date
- Diet data
- Type of diet
- Start date
- Stop date
- Adverse event section
- Adverse event
- Event date
- Treatment involved
- Treatment discontinuation / dose reduction
- New medication / new dose
- Visit data
- Treatment modality
- Anthropometric features (weight, height, blood pressure)
- Biochemical data
- Calculi data
- Patient’s self-monitoring
- ERKNet member: EUROCYS is part of ERKNet registry so patients can be directly included via the ERKReg data base by using the ethical ERKNet consent form. Please make sure to check with your local ethics committee if additional amendments are required.
- Non-ERKNET member: please make sure to obtain ethical approval before including patients.
- Before any data collection, patients are required to sign the ERKNet consent form, agreeing to enter data into the ERKReg registry.
- A specific information note on EUROCYS must be given to the patients to explain them the purpose of the sub-registry and all their legal rights.
For more information please contact: Yann Nedelec (yann.nedelec[at]aphp.fr)