Objective: To determine whether the existing family data for infantile hypertrophic pyloric stenosis (IHPS) are sufficient for the purposes of establishing the mode of inheritance of this condition.
Design: Reanalysis of the familial aggregation patterns exhibited by IHPS, using data from several published family studies.
Conclusions: Due to several limitations of the available family data for IHPS, the results of this analysis should be interpreted cautiously. Within the context of these limitations, the familial recurrence pattern among monozygotic cotwins and more remote relatives of IHPS probands was found to be inconsistent with generalized single major locus inheritance. The familial recurrence pattern of IHPS is, however, compatible with multifactorial threshold inheritance or the effects of multiple interacting loci. Under a model of multiple interacting loci, no single locus can account for more than a fivefold increase in the risk to first-degree relatives of IHPS probands. In contrast to several earlier reports, this analysis does not support the existence of a maternal factor that contributes to the risk of IHPS in the offspring of affected females.