Heterozygous single nucleotide variants (SNVs) in TBX4 (MIM# 601719) or CNV deletions involving TBX4 and its neighboring TBX2 (MIM# 600747) on 17q23.2 have been described in newborns with acinar dysplasia (AcDys), congenital alveolar dysplasia (CAD), or other primary pulmonary hypoplasias in newborns [13–15]. Here, TBX4 is linked to familial primary pulmonary hypoplasia.