Cerebrotendinous Xanthomatosis (CTX): Remaining Challenges and the Need for International Collaboration

Within the field of CTX, many challenges still remain: CTX is a complex and very heterogeneous disorder with a broad clinical spectrum in which the disease course cannot be clearly predicted due to the lack of genotype—phenotype, either clinical or biochemical, associations. This is especially relevant in view of inclusion of CTX in newborn screening programs, which is expected in the near future. These challenges may be mitigated by strong international collaboration between health care professionals and CTX patient advocacy groups. Setting up an independent international patient registry will help us to further delineate the clinical spectrum in CTX, may help us to establish genotype—phenotype associations, and will help us to establish criteria for starting treatment with chenodeoxycholic acid in countries that want to adopt a watchful waiting policy with implementation of newborn screening. To standardize the clinical characterization of patients with CTX, the development of a clinical disease severity score is much warranted and could be devised using a Delphi consensus procedure in collaboration with international experts.