Since glomerular dopaminergic TH-immunoreactive interneurons in OB release dopamine and GABA, which would inhibit glutamatergic neurotransmission from receptor neurons to mitral cells [37,128,129], it has been suggested that the increased number of inhibitory TH-immunoreactive interneurons might cause hyposmia in PD [127,130]. The gene discussed is TH; the disease is Parkinson disease.