Fetal chylothorax is one of a very few syndromes that can be treated in utero with thoracoamniotic shunting or pleurodesis by OK-432 as two major therapeutic modalities. We report on a fetus with Noonan syndrome and a missense mutation c.182A > C (p.Asp61Ala) of PTPN11 who responded poorly to antenatal pleurodesis by OK-432. Based on our previous publication and this case study, we propose that fetal chylothorax of a distinct genetic origin may respond poorly to OK-432 pleurodesis.