Based on the overlap of additional pathogenic CNV deletions causative for ACDMPV and the presence of hypermorphic single nucleotide variants (SNVs) in the undeleted allele of the enhancer that significantly ameliorated the lethal ACDMPV phenotype by increasing FOXF1 expression, this enhancer was narrowed to the ~10 kb-large most essential region [20,21]. Here, FOXF1 is linked to alveolar capillary dysplasia with misalignment of pulmonary veins.