A Danish cohort of twins with inflammatory bowel disease, Crohn's disease and ulcerative colitis, has previously been collected.
Dr Tine Jess and colleagues from Denmark reassessed this cohort.
The researchers compared clinical characteristics in concordant versus discordant twin pairs, and test twin zygosity genetically.
The research team followed up on disease concordance, and examined NOD2/CARD15 genetic status.
The Danish cohort is 1 of 2 population-based cohorts worldwide and consists of 103 twin pairs.
After median 13 years of follow-up, the team contacted all twins and scrutinized hospital files to reassess disease concordance and obtain phenotype data.
DNA was obtained from 123 twins for analysis of zygosity and prevalence of the three common NOD2/CARD15 mutations.
|44% of Crohn's patients were positive for either 1 or more mutant alleles of NOD2/CARD15|
|American Journal of Gastroenterology|
The researchers found that Zygosity tested genetically was consistent with the former assessment based on questionnaires.
The proband concordance for Crohn's disease remained fairly stable at 64% among monozygotic twins and 4% among dizygotic twins.
The team noted similar clinical characteristics in twins from concordant versus discordant pairs.
The research team observed that 44% of patients with Crohn's disease were positive for either 1 or more mutant alleles of NOD2/CARD15.
For patients with ulcerative colitis, 2% were positive for either 1 or more mutant alleles of NOD2/CARD15.
In addition, the team found that 19% of healthy twins were positive for either 1 or more mutant alleles of NOD2/CARD15.
The allele mutation frequency was 43% among the healthy twins to patients with Crohn's disease.
The team compared this to an allele mutation frequency of 9% among twins to patients with ulcerative colitis patients.
Dr Jess' team commented, “Previous questionnaire assessment of twin zygosity was confirmed by genetic test.”
“Concordance for Crohn's disease remained quite stable and was significantly higher among monozygotic than dizygotic twins.”
“A high NOD2/CARD15 mutation frequency was observed both among Crohn's disease twins and their healthy siblings.”