Total anomalous pulmonary venous return (TAPVR) is a cyanotic congenital heart defect that, without surgical correction, has a high mortality rate in the first year of life. It usually occurs without a family history and has a low recurrence risk. However, we recently reported a large Utah-Idaho family in which TAPVR segregates as an autosomal dominant trait with decreased penetrance. Linkage mapping with highly polymorphic microsatellite markers localizes the disease locus in this pedigree to the centromeric region of chromosome 4 (maximum lod = 6.51 at theta = .00). Apparent genetic anticipation in the pedigree prompted a search for expanded trinucleotide repeats by using repeat expansion detection. We have found no evidence for a trinucleotide repeat expansion that segregates with TAPVR. A vascular endothelial growth-factor receptor that is thought to have a role in vasculogenesis maps near the pericentric region of chromosome 4 and is a candidate gene for both familial and sporadic cases of TAPVR.