Despite the high expression of both ACE2 and TMPRSS2 in the small intestine, germ cells, kidneys, and heart, against the medium level of expression in the lung tissue and low-to-medium expression in the nervous system [21], COVID-19 symptoms did not reflect such differential ACE2 expression, instead, the respiratory symptoms affected most of the cases, and neurological symptoms were found in 30% of hospitalized cases [128], while diarrhea, for instance, was found in a smaller number of cases [129]. The gene discussed is ACE2; the disease is COVID-19.