Table 2.

Possible CRN designs.

Design	Observational vs interventional
	Registry vs RCT
	Cross-sectional vs longitudinal
	Inception vs cohort
	Personalized medicine
Participants	Eligibility criteria for cases
Participants	Inclusion of control subjects, especially important for laboratory and imaging biomarkers
Sites	Number
	Geographical representation
	Targeting special populations who – have been underresearched to date – present with extreme phenotypes
	Closed vs open to new sites after commencement
	Recruitment cap for each site to improve external validity
	Biosamples contribution – mandatory for all sites vs some contributing clinical data only
Data management	Effective IT solutions that are robust over time
	NGS-type storage of extremely large datasets
	Different systems for genomic vs imaging data
	Data dictionary, to ensure consistency of terminology, especially for clinical terms

CRN: collaborative research network; RCT: randomized controlled trials; IT: information technology; NGS: next-generation sequencing.