ACE2 and Kallmann syndrome: In unrelated TwinsUK participants seropositive for SARS-CoV-2 antibodies (N = 32), we assessed whether background ACE2 expression was associated with presentation of one or more core COVID-19 symptoms (fever, persistent cough, anosmia) and/or one or more of the more severe COVID-19 symptoms (shortness of breath, chest pain or chest tightness).