IGKV4-1 and Parkinson disease: In the case of PD, the changes in nAChRs reported were inconsistent, but manifested primarily as decreased expression of α3 mRNA and protein, as well as attenuated density of the receptors containing these subunits in the brain; increased compensatory expression of α7; an unchanged or lowered level of α4β2; and raised α6 and reduced β3, both are uncommon types of nAChRs.