As HS6ST1 deficiency is lethal in mice primarily during the later embryonic stages, resulting in abnormal angiogenesis in the labyrinthine zone of the placenta along with aberrant lung morphology similar to that observed in pulmonary emphysema (Habuchi et al., 2007), HS6ST1 is considered to be essential for angiogenesis also in the pulmonary circulation. The gene discussed is HS6ST1; the disease is pulmonary emphysema.