PRKN and Parkinson disease: We do note here though that there is some controversy over the exact implication of the presence of Lewy bodies in the disease, as some unusual forms of PD (such as Parkin mutations causing early onset PD; Takahashi et al., 1994) present without Lewy body pathology and in contrast incidental Lewy body disease is defined as the presence of Lewy bodies without clinical signs of PD.