A team from Winnipeg, Canada, investigated generational differences in the age at diagnosis (AAD) in inflammatory bowel disease (IBD).
A population-based IBD Research Registry, using comprehensive administrative databases in the province of Manitoba, Canada, was established in 1995. This included both clinical and demographic information for the patients.
The researchers contacted subjects within the Research Registry who reported having any family members with IBD, and their family members, for verification of diagnosis and AAD.
Differences in AAD between familial pairs were calculated.
In addition, to assess whether duration of follow-up accounted for generational differences in AAD, they computed the mean AAD for subjects with and without family histories of IBD. This was based on age at the time of interview (< 45 versus ≥ 45 years of age).
Of the 2445 persons with IBD in the Research Registry, 548 reported positive family histories, and 315 of these (58%) were reached by telephone.
There were found to be 169 Crohn's disease and 146 ulcerative colitis subjects with positive family histories.
The mean AADs for the parents, aunts/uncles, and grandparents were significantly greater than the mean AADs for the children, nieces/nephews, and grandchildren, respectively.
| No significant difference in genetic anticipation observed.
| American Journal of Gastroenterology |
There was a doubling of the mean AAD when comparing the grandparent/grandchild cases with the parent/child or aunt/uncle-niece/nephew cases.
No statistically significant difference in anticipation was observed, whether or not the older generation was male or female, or had Crohn's disease or ulcerative colitis.
The investigators found that AAD was substantially greater for those interviewed at ≥ 45 years of age, for subjects with and without family histories.
However, there was no substantial difference in mean AAD between familial and nonfamilial subjects.
Author E. M. Faybush, of the University of Manitoba, said on behalf of the group, "The present study has demonstrated that there is a tendency for children to be younger than their parents at the time of diagnosis of familial IBD.
"This difference in mean AAD is almost doubled for grandparent/grandchild pairs."
"However, these differences are most likely due to a bias based on length of follow-up or recent multigenerational temporal changes in the risk of IBD, or both," it was concluded.