title: Familial Mediterranean fever in siblings.
abstract: OBJECTIVE
  Genetic and environmental factors have been implicated in disease severity and development of amyloidosis in familial Mediterranean fever (FMF). We investigated similarities in clinical characteristics, disease severity, and treatment response within siblings with FMF.
  
  
  METHODS
  The study group consisted of 2 or more siblings who were followed in our center with the diagnosis of FMF. Siblings were evaluated for demographic data, clinical and laboratory disease features, genetic analysis of MEFV mutations, and disease severity score. The intraclass correlation coefficient (ICC), which can be interpreted as the expected correlation between 2 siblings, was used to reflect within-family similarity.
  
  
  RESULTS
  The study included 67 pediatric patients from 31 different families. When we investigated the similarity of siblings after adjusting for genetic effects, we found very low ICC with p > 0.05 in the majority of clinical features, disease severity, and colchicine dosages. However, age at disease onset, age at onset of therapy, attack-free acute-phase reactant levels, and presence of amyloidosis were found to be similar within siblings (relatively high ICC with p < 0.05).
  
  
  CONCLUSIONS
  Siblings with FMF had different clinical findings and disease severity. They had similar amyloidogenic potential, proven by both similar presence of amyloid and increased levels of acute-phase reactants between attacks. Our findings strongly support that genetic factors may be more dominant in the development of amyloidosis.
authors.affiliation: Department of Pediatric Nephrology and Department of Biostatistics, Ankara University School of Medicine, Ankara, Turkey.
authors.forename: Z Birsin
authors.initials: ZB
authors.lastname: Özçakar
authors.forename: Beyza Doganay
authors.initials: BD
authors.lastname: Erdogan
authors.forename: Atilla H
authors.initials: AH
authors.lastname: Elhan
authors.forename: Fatoş
authors.initials: F
authors.lastname: Yalçinkaya
mesh_terms: D000293:Adolescent; D000686:Amyloidosis / Q000453:epidemiology / Q000235:genetics; D002648:Child; D002675:Child, Preschool; D003078:Colchicine / Q000627:therapeutic use*; D003598:Cytoskeletal Proteins / Q000235:genetics*; D018450:Disease Progression; D004305:Dose-Response Relationship, Drug; D010505:Familial Mediterranean Fever / Q000150:complications / Q000188:drug therapy* / Q000235:genetics*; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D009154:Mutation / Q000235:genetics*; D000071198:Pyrin; D012307:Risk Factors; D012720:Severity of Illness Index; D035781:Siblings; D013997:Time Factors; D055815:Young Adult
chemical_list: D003598:Cytoskeletal Proteins; C000604192:MEFV protein, human; D000071198:Pyrin; D003078:Colchicine