Cardiac sympathetic denervation precedes nigrostriatal loss in the E46K mutation of the α-synuclein gene (SNCA)

Here we report the case of an asymptomatic carrier of the E46K substitution in alpha-synuclein gene where we have documented that cardiac sympathetic denervation precedes nigrostriatal dopaminergic loss. She has been followed up regularly with standard neurological examination, UPDRS, neuropsychological formal testing, parkinson disease sleep scale-PDSS, Epworth scale, Hamilton-D scale, SCOPA Aut, orthostatic hypotension test, brief smell identification test, polysomnography, cerebral 123-I-FP-CIT SPECT, and, 123I-MIBG cardiac scintigraphy. She shows no presence of orthostatic hypotension. Olfactory test results demonstrate normal limits. In the PSG the nocturnal sleep shows mild abnormalities although the sleep efficiency and stage proportion remain under normal limits. The 123-I-FP-CIT SPECT is normal; in contrast, the 123I-MIBG cardiac scintigraphy shows a complete lack of isotopic uptake compatible with a severe sympathetic myocardial denervation. This example of monogenic autosomal dominant parkinsonism due to an alpha-synuclein mutation favours the hypothesis that peripheral autonomous nervous system involvement occurs earlier than the CNS degeneration.