Clinical registry and biobanking
In ENISNIP, we aim to include a maximum number of patients with all forms of CIP/HSAN. Our cohort currently covers a total of >300 index patients. We continuously enroll more patients through recruitment in our institutions and collaboration with external partners worldwide.
We develop a harmonized data registry for CIP/HSAN, which covers family and own medical history, CIP/HSAN symptoms, physical examination, neurophysiological, imaging, laboratory and biopsy studies, and genetic diagnosis.
ENISNIP aims to establish a decentralized, transnational ‘virtual’ repository for patient-derived biological samples. The biobank will support key scientific activities of ENISNIP by facilitating access to and supporting sharing of samples within the consortium.
By harmonizing and re-evaluating the genetic data of existing patient cohorts at ENISNIP project sites and collaborating institutions, we were able to identify 70 novel likely disease-causing variants in known HSAN genes. These data were validated by additional functional analyses and completed with clinical data provided by the project partners. The final results will be published soon and variants will be submitted in ClinVar to make them accessible for clinicians and scientists.
We re-analyze ‘unsolved’ cases by re-evaluating existing data and re-sequencing the samples using state-of-the-art sequencing techniques and pipelines. Additionally, we continously recruit new patients and thereby enlarge our patient cohorts. By establishing an accurate diagnosis in a subset of those patients, we directly impact patient care. At the same time, comprehensive clinical characterization and genetic testing will ensure build-up of sufficiently large cohorts of genetically unsolved cases for gene discovery studies.
If analysis of WES data fails to pinpoint a likely gene defect, cases will be considered for a ‘beyond the exome’ approach. ‘Unsolvable’ patients with highly recognizable phenotypes for whome relevant biomaterials are available (e.g., PBMC or fibroblasts for generation of iPSCs) may be additionally analyzed using long-read ‘third generation’ whole-genome sequencing (WGS) on an Oxford Nanopore PromethION sequencer. This does not only ensure full exploration of the noncoding DNA for these cases (gene-regulatory sequences, introns and intergenic regions) but also uncovers variants usually not (reliably) detected by short-read sequencing technologies, i.e., structural variants and repeat expansions.
Functional analyses are carried out to determine the pathogenic potential of novel variants and thus far unknown genes which have been found by sequencing analyses. For this purpose, we use different approaches: In addition to patient-derived fibroblasts and iPSC cells, we study mouse models which represent specific HSAN subtypes and help us decipher deregulated processes in the organism of HSAN patients. One particular biological process that ENISNIP is focusing on is the sphingolipid mechanism, which is deregulated in HSAN patients with pathogenic variants in SPTLC1 and SPTLC2.