title: Rare factor deficiencies.
abstract: OBJECTIVE
  By definition, rare factor deficiencies have a prevalence of less than 200,000 in the US population, or an incidence of less than one in 2000 in Europe. The very small numbers of patients with rare disorders present challenges in diagnosis, evaluation of bleeding risk and treatment. Use of new assays, full genome sequencing, and global clotting assays will significantly improve diagnosis of patients with rare bleeding disorders.
  
  
  RESULTS
  In addition to new assays available for monitoring patients, new therapy, both recombinant and plasma derived, is now available. Registries and clinical trials have demonstrated decreased bleeding and improved outcomes when patients are treated with these agents. Expanding international registries have been initiated to correlate genotype and bleeding phenotype in conjunction with global assays.
  
  
  CONCLUSIONS
  Ongoing research continues to expand our understanding of the pathophysiology of rare factor deficiencies. This work complements medical practice to incorporate early diagnosis and new treatment options for patients, resulting in safer and less sensitizing regimens and much improved clinical outcomes.
authors.affiliation: Pediatric Hematology Division, Childrens Hospital, Orange, California, USA.
authors.forename: Loan
authors.initials: L
authors.lastname: Hsieh
authors.forename: Diane
authors.initials: D
authors.lastname: Nugent
mesh_terms: D001779:Blood Coagulation Factors / Q000627:therapeutic use*; D020147:Coagulation Protein Disorders / Q000175:diagnosis / Q000235:genetics / Q000628:therapy*; D006801:Humans; D035583:Rare Diseases / Q000175:diagnosis / Q000235:genetics / Q000628:therapy*
chemical_list: D001779:Blood Coagulation Factors