PD-causing Genes Research Articles

LRRK2 Low-penetrance Mutations (Gly2019Ser) and Risk Alleles (Gly2385Arg)—Linking Familial and Sporadic Parkinson’s Disease

The identification of mutations in the leucine-rich repeat kinase 2 (LRRK2) gene as a cause of autosomal dominant Parkinson's disease (PD) was a major step forward in the genetic dissection of this disorder. However, what makes LRRK2 unique among the known PD-causing genes is that a low-penetrance mutation, Gly2019Ser, is a frequent determinant not only of familial, but also of sporadic PD in several populations from South Europe, North Africa and Middle East. Moreover, a different polymorphic variant, Gly2385Arg, is a frequent risk factor for PD among Chinese and Japanese populations. Currently, the Gly2019Ser and Gly2385Arg variants represent the most relevant PD-causing mutation and risk allele, respectively, linking the etiology of the familial and the sporadic forms of this disease. Understanding how the dysfunction of LRRK2 protein leads to neurodegeneration might provide crucial insights for unraveling the molecular mechanisms of PD and for developing disease-modifying therapies.

S.11.03 Can cells repair the brain in Parkinson's disease?

Parkinson’s disease (PD) is a neurodegenerative movement disorder characterized by the loss of dopaminergic neurons in the substantia nigra of the midbrain. To date, a number of PD-causing genes have been found, including SNCA, LRRK2, VPS35, PARK2, PINK1, DJ-1, ATP13A2, and most recently CHCHD2. Mutations in these genes range from point mutations to larger exonic rearrangements including deletions and duplications. This study aimed to detect possible copy number variation (CNV) in the known PD-causing genes in a cohort of South African patients with PD. Multiplex Ligation-dependent Probe Amplification (MLPA) analysis was performed on a total of 210 South African PD patients, and possible CNVs were verified using quantitative real time PCR. No homozygous or compound heterozygous exon rearrangements in the genes analysed were found in the patient group. A heterozygous PARK2 exon 4 deletion was found in a sporadic patient with an age at onset of 51 years. Sanger sequencing did not reveal any additional mutations in PARK2 in this patient. Combining our results with that of previous studies in a South African cohort, the frequency of exonic rearrangements in the known PD-causing genes is only 1.8% (8/439 patients). In conclusion, CNV in the known PD-causing genes are a rare cause of PD in a South African cohort, and there may be as yet unknown genetic causes of PD that are specific to patients of African ethnicity.