A novel ATP13A2 variant causing complicated hereditary spastic paraplegia.

BACKGROUND

ATP13A2 is a monogenic causative gene of Parkinson's disease, whose biallelic mutations can result in Kufor-Rakeb syndrome. Biallelic mutations in ATP13A2 have also been reported in pure or complicated hereditary spastic paraplegia (HSP). Here, we report clinical, neuroimaging, and genetic findings from a patient with a novel homozygous mutation in ATP13A2 presenting with HSP plus parkinsonism.

METHODS

Whole genome sequencing was performed on the patient, a 46-year-old Chinese woman from a consanguineous family, to identify the genetic cause. Furthermore, functional studies of the identified ATP13A2 mutation were conducted.

RESULTS

The patient initially presented with abnormal gait because of lower-limb spasticity and recurrent seizures. Parkinsonism (presenting as bradykinesia and rigidity) and peripheral neuropathy in lower limbs further evolved and resulted in her eventual use of a wheelchair. Symmetrically decreased dopamine transporter density was detected within the bilateral putamen and caudate nucleus in dopamine transporter-positron emission tomography. Genetic analysis revealed a novel homozygous missense mutation in ATP13A2 (c.2780 T > C, p.Leu927Pro), which was heterozygous in the patient's parents and son. Functional studies suggested that this mutation results in the reduced expression and altered subcellular localization of ATP13A2.

CONCLUSIONS

Our report broadens the genetic and phenotypic spectrum of ATP13A2-related HSP. Further research is needed to fully elucidate the mechanism linking ATP13A2 variants to HSP.