Recent studies in humans and mice have shown that ILC2s are also associated with severe asthma by their capacity to become resistant to corticosteroids through TSLP and signal transducer and activator of transcription 5.2, 3, 4 Therefore, analyzing ILC2s in patients with asthma not only indicates the presence of an ILC2-mediated inflammation but may also serve as a biomarker for asthma severity and steroid resistance, which may be useful for personalized medicine. The gene discussed is TSLP; the disease is asthma.