The working groups regularly conduct online surveys to collect data on specific research questions concerning individual diseases. This instrument has proven highly successful as it allows to quickly obtain information from large numbers of patients with rare conditions. The surveys are set up and circulated by the ERKNet central office to the ERKNet member mailing list.

Open ERKNet Surveys

ERKNet Survey on Gitelman Syndrome

This survey is undertaken on behalf of the Tubulopathies Working Group and initiated by Ewout Hoorn and Michiel Wieers.

Eligible patients are pediatric or adult patients with a clinical and/or genetic diagnosis of Gitelman syndrome – patients with acquired Gitelman or a Gitelman-like syndrome due to variants other than SLC12A3 are not eligible. 

To access the survey, please follow click here. You will be directed to an electronic data capture system. Please note that the data entry for each patient should be completed in one go (~15 min/patient).

If you have further questions to this porject, please contact Ewout Hoorn [e.j.hoorn[at]] and  Michiel Wieers [m.wieers[at]] directly. 

ERKNet Survey on Severity in function of the age-at-onset of hereditary podocytopathies

The goal of this project, initiated by our ERKNet member Kalman Tory and his colleagues, is to precisely characterize the relationship between the degree of proteinuria and the age at diagnosis in hereditary podocytophathies. They expect to determine the highest age at which a genetic podocytopathy can present with a severe degree of proteinuria, and thus to limit the number of patients with late-onset SRNS referred for genetic investigation.

If you would like to participate in the survey, please click on the following link:

Please include only patients (children and adults) with a proven hereditary podocytopathy. Multiple affected family members can be included. It is important to provide data at the first diagnosis of proteinuria (before the administration of ACEI or ARB).

We thank you very much for your participation. For further questions please contact Kalman Tory [tory.kalman[at]].

ERKNet Survey on Cut-Off Values for Phosphate and PTH

ERKNet collects serum phosphate and PTH values for each visit as Key Performance Indicators (KPI). Regarding serum phosphate, so far, the focus has been on age and gender-specific upper cut-off values, even though the lower cut-off value is of importance, too. Moreover, different laboratory assays have different specificities and cut-off values. Likewise, different PTH assays provide different ranges of normal. 

This survey, initiated by the Pediatric CKD and dialysis Working Group, aims to obtain the cut-off values of all ERKNet centers according to their daily practice for valid analysis and interpretation of the two essential KPI, serum phosphorus and PTH. Please submit the information in this document. 

If you have any questions, please contact Claus Schmitt [], Justine Bachhetta [] or Jerome Harambat [].


ERKNet Survey on patients with SLC26A1 or SLC13A1 mutations

Although SLC26A1 and SLC13A1 are considered critical for sulfate reabsorption in the kidney, little is known about mutations of these transporters in humans. Therefore, our ERKNet members from Charité in Berlin plan to collect data from patients with these mutations. They will focus on sulfate-related symptoms, i.e. musculoskeletal symptoms as well as kidney stones, to better characterize the clinical phenotype of patients with SLC26A1 and SLC13A1 mutations.

If you have identified patients with SLC26A1 or SLC13A1 mutations (heterozygous or homozygous), they would be very pleased to collaborate with you on this project. Please email Anja Pfau [anja.pfau[at]] and Felix Knauf [felix.knauf[at]].

ERKNet Survey on the prevalence of PKD2-founder variant in Europe

In a joint project with collaborators from Taiwan, Jan Halbritter is asking on behalf the AD-stuctural kidney disorders working group for your help regarding the identification of additional ADPKD-patients with a certain disease-causing variant in PKD2. This very PKD2 variant has recently been identified to constitute a frequent founder variant in Taiwan (PMID: 35778421), and by preliminary analyses seems to represent a relatively frequent PKD-variant in Europe too (NM_000297.4 (PKD2): c.2407C>T (p.Arg803Ter),

Identification of additional patients with this PKD2-variant will help to build up a European cohort (n=x) in addition to the existing cohort from Taiwan (n=200) to jointly investigate modifiers of disease.

As ethical approval is an important factor, only patients with signed informed consent from ERKReg are eligible for the survey. Rest assured that your responses will remain completely confidential, and no identifying information will be collected. 

To participate in the survey, please follow this link:

We kindly request your assistance in completing the survey. Should you have any questions or concerns regarding the survey or the research itself, please feel free to contact Jan Halbritter [jan.halbritter[at]] directly. 


ERKNet Survey on GATA3 mutations causing HDR syndrome

Our ERKNet members from HCP Radboud UMC Nijmejen are conducting a survey to collect cases of GATA3 mutations causing HDR syndrome (hypoparathyroidism, sensorineural deafness, and renal dysplasia) to examine their electrolyte balance, in particular related to Mg homeostasis. Since these patients are very rare, at this stage they just want to collect the names of physicians who care for these patients. They will then ask further questions at a later stage.

If you have patients with GATA3 pathogenic variants and would be interested in collaborating in this project please send an e-mail to Jeroen de Baaij (jeroen.debaaij[at]

ERKNet Survey on Anesthesia and ICU Care in Pediatric Kidney Transplantation

The research team at ERKNet HCP Radboud UMC Nijmejen is conducting a survey among (pediatric) anesthesiologists and/or ICU doctors about their care for pediatric kidney transplant patients. The results of the survey could serve as a basis for a consensus guideline.

If you are interested to participate, please get in touch with Marieke Voet, pediatric anesthesiologist (Marieke.Voet[at] and Marlies Cornelissen, pediatric nephrologist (Marlies.Cornelissen[at] 

ePAG driven ERKNet Survey on Electrolyte Supplement Products

Our ERKNet patient advocacy group (ePAG) has started an inventory project to find out which electrolyte supplement products are available and what the reimbursement practice is in the individual EU member states. The results of this survey will allow us to create a list of equivalent products (to be published on the ERKNet Website) and lobby for equal reimbursement policies throughout the EU.

If you are interested to help us identifying the main electrolyte supplement products prescribed in your country, please get in touch with our ePAG patient manager Vera Corneslius ( and the ePAG lead Susana Carvajal Arjona (s.carvajal[at] 


Closed ERKNet Surveys

ERKNet research surveys conducted between 03/2019-06/2023

Persistent hypotension in anephric children | June 2023

Investigators: Justine Bacchetta; Jerome Harambat; Stephanie Tellier, Toulouse

Aim: To gather observations of prolonged hypotension in anephric children, a very rare but serious event.


International survey of Inverted Formin nephropathy | May 2023

Investigator: Peter Conlon, Dublin

Aim: To collect clinical and genetic data from patients or families with inverted formin nephropathy treated by ERKNet members to understand the history of this rare disease. 


TRCP6 Nephropathy Project | May 2023

Investigator: Peter Conlon, Dublin 

Aim: To study TRCP6 nephropathy patients or families to gain insight into the disease's history.


Cystinosis in your centre 2022 | April 2022

Investigators: Aurélia Bertholet-Thomas, Lyon; Justine Bachetta, Lyon; Elena Levtchenko, Leuven (WG metabolic nephropathies)

Aim: To update knowledge on the global health situation of patients with nephropathic cystinosis, to highlight persistent territorial disparities. 


ERKNet collaboration request | January 2022

Investigators: Roman-Ulrich Müller, Christian Frezza, Cologne

Aim: To look for partners that can provide tumour samples from HLRCC in the framework of scientific collaboration.


NDSAIs in NDI or Bartter | November 2021

Investigators: Detlef Bokenhauer, Francesca de Zen, Francesco Emma (WG tubulopathies)

Aim: To study the effect of long-term use of non-steroidal anti-inflammatory drugs (NSAID) on kidney function (as assessed by creatinine). 

Response rate: 455

Current status: Data is being analyzed


GAMOS survey | Oktober 2021

Investigators: Dieter Haffner, Nele Kanzelmeyer, Hannover (WG hereditary glomeruopathies)

Aim: 1) to further characterize the clinical phenotype, especially specifying the renal and extra-renal manifestations, 2) to identify genotype-phenotype correlations, and 3) to collect information regarding clinical management and outcome.


Cinacalcet in children | October 2021

Investigators: Justine Bachetta, Sacha Flammier, Dieter Haffner, Rukshana Shroff, Claus Peter Schmitt (WG pediatric CKD and Dialysis)

Aim: To analyze the clinical indication, safety and efficacy of this calcimimetic in the youngest dialysis populations.


Alpart study | October 2021

Investigators: Titia Lely, Albertien van Eerde, Utrecht (WG hereditary glomerulopathies)

Aim: Retrospective cohort study to compare pregnancy outcomes of women with COL4A3-5 related disease (Alport syndrome, AS) to women with other chronic kidney diseases.

Response rate: 139

Current status: Data is being analyzed


Long-term outcome of childhood idiopathic nephrotic syndrome | July 2021

Investigators: Giulia Bassanese, Marina Vivarelli, Licia Peruzzi (WG immune glomerulopathies)

Aim: To collect data that will improve the understanding of the natural history of idiopathic nephrotic syndrome


Membranous nephropathy in childhood | February 2021

Investigators: Marina Vivarelli, Rome; Julien Hogan, Paris; Pierre Ronco, Paris (WG hereditary glomerulopathies)

Aim: To identify European centres that have children affected by this rare glomerular disease, to set up a platform for a larger study for appropriate antigenic screening of these children


Patients with mutations in the sodium-phosphate cotransporter geneses (SCL3A3, SLC3A1) | February 2021

Investigators: ERKNet/ESPN. Dieter Haffner, Max Brunkhorst, Hannover; Francesco Emma, Rome;  Elena Levtchenko, Leuven. (WG tubulopathies)

Aim: To analyze the natural history of these rare diseases, address genotype-phenotype associations, and to explore the use of phosphate supplementation.

Response rate: 188

Current status: Survey closed on May 30, 21. Data is being analyzed.


Survey on primary coenzyme Q10 deficiency | Oktober 2020

Investigators: ERKNet, PodoNet, ESPN. Stefania Drovandi, Genoa; Beata Lipska, Gdansk, Franz Schaefer, Heidelberg (WG hereditary glomeruopathies)

Aim: To analyze the natural history of the disease, describe the spectrum and extent of extrarenal disease manifestations, address genotype-phenotype associations, and further explore the efficacy and clinical utility of CoQ10 treatment.

Current status: Drovandi et al., April 2022, Kidney International. Variation of the clinical spectrum and genotype-phenotype associations in Coenzyme Q10 deficiency associated glomerulopathy


Survey on HNF1B | June 2020

Investigators: Joost Schanstra, Stephane Decramer, Toulouse (WG CAKUT)

Aim: To collect data on a large set of patients with HNF-1ß gene anomalies and assess the influence of the type of HNF-1ß anomaly, transmission and ultrasound presentation on disease progression.

Response rate: 109

Current status: Data collection closed on June 20, 2021. Data is being analyzed


Children on immunosuppressant medication with COVID-19 | March 2020

Investigators: Kjell Tullus, Matko Marlais, London; Marina Vivarelli, Rome (WG Immune Glomerulopathies); Lars Pape, Hannover, Burkhard Tönshoff, Heidelberg (WG Pediatric Transplantation)

Aim: To gather information on cases of COVID-19 in children on immunosuppressant medication from the global pediatric community. Provide information which may help for clinical decision making and advice to patients.

Response rate: 125

Current status: Results published.

(1) Marlais M, Wlodkowski T, Vivarelli M, Pape L, Tönshoff B, Schaefer F, Tullus K. The severity of COVID-19 in children on immunosuppressive medication. Lancet Child Adolesc Health. 2020 Jul;4(7):e17-e18. doi: 10.1016/S2352-4642(20)30145-0. Epub 2020 May 13. PMID: 32411815; PMCID: PMC7220160. 2nd publication in press.

(2) Marlais M, Wlodkowski T, Al-Akash S, Ananin P, Bandi VK, Baudouin V, Boyer O, Vásquez L, Govindan S, Hooman N, Ijaz I, Loza R, Melgosa M, Pande N, Pape L, Saha A, Samsonov D, Schreuder MF, Sharma J, Siddiqui S, Sinha R, Stewart H, Tasic V, Tönshoff B, Twombley K, Upadhyay K, Vivarelli M, Weaver DJ, Woroniecki R, Schaefer F, Tullus K. Arch Dis Child. 2020 Dec ;106(8):798-801. doi: 10.1136/archdischild-2020-320616. Online ahead of print.


Survey on Fanconi-Bickel- Syndrome | April 2020

Investigators: Francesco Treppicione, Naples;  Aude Servais, Paris (WG Metabolic Nephropathies)

Aim: To obtain information on clinical features, diagnosis, therapy, and outcome of this ultrarare disease to get a close-up view of the disease and its variabilities to improve patient care.

Response rate: 94, data collection ongoing until 15th December 2020

Current status: Manuscript in preparation.


Survey on Nephrogenic Diabetes Insipidus |June 2019

Investigator: Detlef Bockenhauer, London (WG Tubulopathies)

Response rate: 315

Current status: Results published. Lopez-Garcia et al., 2020. Treatment and long-term outcome in primary nephrogenic diabetes insipidus


ANCA associated vasculitis in childhood | December 2019

Investigators: Kjell Tullus, London; Marina Vivarelli, Rome (WG Immune Glomerulopathies)

Aim: better understanding of the burden of this disease, current treatment practices and long-term outcomes.

Response rate: 375, data are currently being analyzed

Current status: Results published. Marlais et al., AJKD 2022. Clinical Factors and Adverse Kidney Outcomes in Children With Antineutrophil Cytoplasmic Antibody–Associated Glomerulonephritis. DOI:


Dent’s disease type 1 Survey | November 2019

Investigators: Gema Ariceta, Barcelona(WG Tubulopathies)

Aim: To investigate the prevalence, genetic variability, the clinical phenotype, and the long-term outcome of patients, as well as current treatment practices around Europe.

Response rate: 103

Current status: Draft manuscript finished.


Survey on Hantavirus | September 2019

Investigators: Roman Müller, Cologne

Aim: To prepare interactions on Hantavirus infections causing kidney failure, a first insight into the situation at ERKNet centres has been obtained.


Cystinuria Survey | September 2019

Investigators: Aude Servais, Paris, for the WG Metabolic and Stone Disorders

Aim: To create a specific cystinuria registry affiliated with ERKReg to better understand the long-term outcome of patients with cystinuria, as well as current treatment practices.

Response rate: 30


Survey on the current status of HRQoL assessment in ERKNet | July 2019

Investigators: Lars Pape, Hannover, for the QoL & Transition Taskforce

Aim: To measure and compare the quality of life of children and adults with rare kidney diseases and to develop and validate improvement strategies. The survey measures the current status of HRQoL assessment in ERKNet centres. 

Response rate: 29


Survey on Nephrogenic Diabetes Insipidus |June 2019

Investigator: Detlef Bockenhauer, London (WG Tubulopathies)

Response rate: 315

Current status: Results published.

Lopez-Garcia et al., 2020. Treatment and long-term outcome in primary nephrogenic diabetes insipidus


Landscape of current practice in aHUS treatment with eculizumab in Europe | May 2019

Investigator: Michal Malina, Newcastle (WG TMA)

Aim: To gather experience about the current practice of eculizumab treatment in countries throughout Europe

Response rate: 86, publication in preparation


Decline in GFR in FHHNC survey | April 2019

Investigators: Martin Konrad (WG tubulopathies)

Aim: Analysis of the evolution of renal function in FHHNC, either caused by CLDN16 or 19 defects

Response rate: 259 (56 from ERKNet centres)

Current status: Results are currently being analyzed