Left heart obstructive congenital cardiovascular malformations [CCVM], including aortic stenosis [AS], coarctation of the aorta [CoAo], and hypoplastic left heart syndrome [HLH] are thought to have common genetic risks. Using spatial analysis we sought linkage between these groups as well as defining the environmental risk of each group separately.
102 CoAo, 60 AS, 77HLH and 1990 population based controls were entered into a spatial database for Maryland and the District of Columbia. Spatial analysis was carried out using Bernoulli method for case control comparisons for each CCVM compared with controls. Spatial analysis was then carried out using the Bernoulli method comparing the distribution of HLH with respect to AS and then with respect to CoAo looking for areas in which HLH was over represented with respect to the other CCVM. Regions and cases identified by spatial analysis were further analyzed using the extensive dataset of sociodemographic, medical, and exposure variables available for all cases and controls.
Isolated AS is clustered in Maryland in a region of orchards within the Monocacy watershed. Isolated CoAo is clustered in Maryland in the southern Maryland peninsula with risks for the cluster of maternal exposure to solvents and residency at conception in cropland. HLH occurs in regions of increased prevalence with respect to AS only in regions where AS is not present. HLH occurs in regions of increased prevalence with respect to CoAo in a tightly defined region of Baltimore characterized by TRI release of solvents, and by industrial land use. Within this region concurrent cases of AS and CoAo are present. The cases of AS in this region in association with CoAo are iuncreased with odds of 18.2, 95%CI 4.0, 81.9. Analysis of the HLH cluster with respect to CoAo by racial groups comparing cases to controls confirms the cluster in all groups. Residency in the cluster is associated with later prenatal care and lesser paternal education for white infants but these associations are not present for black infants.
We speculate that in areas of environmental exposures a common genetic substrate may result in more severe left heart obstruction based on genetic environmental interactions. This increased severity is expressed as increased prevalence of HLH, association of AS with CoAo in this region, and decreased prevalence of simple CoAo in this region.
(1) Children's National Medical Center
(2) Georgetown University Medical Center