PRKN-Gene-Related Parkinsonism: An Experience from a Tertiary Centre and Literature Review of Asian Cohort.

Abstract

Background: PRKN-related parkinsonism represents one of the most common types of genetically determined Parkinson's disease (PD). However, the literature among the Asian ethnicity, particularly in the Indian context, is limited.

Objective: To study the clinico-genetic profile of patients with PRKN-related parkinsonism and to review the previously reported cases of PRKN-related parkinsonism from Asia.

Methods: A retrospective chart review from a tertiary neurology centre of patients with genetically confirmed PRKN-related parkinsonism. Additionally, we consolidated the Asian cohort from a detailed systematic review of the literature. We utilised the Movement Disorders Society gene cohort for comparison with the world literature.

Results: We recruited 16 cases (males = 10, Early onset Parkinson disease (21 to <50 years age at onset)) of PRKN-related parkinsonism with a median age at onset of 28.5 years (range 14-46). Symptoms included parkinsonism (n = 15), dystonia (n = 10), postural instability (n = 7), freezing of gait (n = 5) and non-motor symptoms (NMS) (n = 10). The commonest symptom at onset was tremors (n = 10). Levodopa responsiveness was observed in all cases with drug-induced dyskinesia in eight (50%). Thirteen cases were homozygous, while three were compound heterozygotes, resulting in 19 variants (novel = 5). Exon deletion was the most common (n = 12). The extended Asian cohort comprising 294 cases had a high prevalence of EOPD (n = 186/257, 72.4%) and familial cases (n = 166/252, 65.9%). Deletion/duplication was the common mutation detected (n = 215, 73.1%). The presumed familial cases had a significantly higher frequency of rest tremors, bradykinesia, postural instability, NMS, dyskinesia and sleep disorders.

Conclusion: This largest single-centre study from India adds 16 new cases and five novel variants to PRKN literature. In addition, it consolidates the Asian cohort of PRKN elucidating its unique attributes.