Table 1.

Characteristics of familial and sporadic Crohn’s disease in patients and healthy relatives

Familial CD	Sporadic CD
Patients
Younger age at presentation	Onset al the classical peak age for IBD
Predominantly ileal involvement	Predominantly colonic involvement
Penetrating/stenosing phenotype	Less frequently complicated
More frequent extraintestinal manifestations	Less frequent extraintestinal manifestations
More frequent NOD2/CARD15 mutations	NOD2/CARD15 mutations < 50% of patients
Higher prevalence of anti-glycan antibodies	NOD2/CARD15 mutations associated with an increased sero-reactivity to microbial antigens
Impaired intestinal permeability associated with NOD2/CARD15 variants	Impaired intestinal permeability in < 50% of patients
Environmental factors: Smoking	Environmental factors: Smoking, diet?
Healthy relatives
Genetic concordance of IBD4 locus in families with smokers	No reported genetic concordance
ASCA trait	Increased sero-reactivity to microbial antigens, also correlating with NOD2/CARD15 genotype
Abnormal intestinal permeability	Abnormal intestinal permeability in < 40% of relatives

IBD: Inflammatory bowel disease; NOD2/CARD15: Nucleotide oligomerization domain 2/caspase recruitment domain 15; ASCA: Anti-Saccharomyces antibodies; CD: Crohn’s disease.