Alpha-synuclein gene duplication: marked intrafamilial variability in two novel pedigrees

Area of Science:

• Genetics
• Neurology
• Molecular Biology

Background:

• Alpha-synuclein (SNCA) gene multiplications are a rare cause of autosomal dominant Parkinson's disease (PD).
• Understanding the genetic basis of PD is crucial for developing targeted therapies.

Purpose of the Study:

• To investigate the clinical presentation of Parkinson's disease associated with SNCA duplication.
• To compare the phenotypes of patients with three versus four copies of the SNCA gene.

Main Methods:

• Description of two novel families with autosomal dominant PD linked to SNCA duplication.
• Clinical comparison of patients with three or four SNCA copies.

Main Results:

• Family A exhibited early-onset PD with variable nonmotor features (dysautonomia, cognitive deficits, psychiatric disturbances).
• Family B showed a spectrum from early-onset PD-dementia to late-onset PD with mild cognitive impairment.
• Four SNCA copies correlated with earlier onset of motor and nonmotor symptoms compared to three copies.

Conclusions:

• SNCA duplications present a wide clinical spectrum, even within families.
• Four SNCA copies are associated with a richer phenotype and earlier symptom onset.
• Unidentified genetic or environmental factors may modify the clinical presentation.