Screening LRRK2 gene mutations in patients with Parkinson’s disease in Ghana

Abstract

The leucine-rich repeat kinase 2 (LRRK2) gene is associated with autosomal dominant Parkinson disease (PD) [1]. Its most common mutation G2019S may account for 3–6% of familial and 1–2% of sporadic PD cases. This mutation’s frequency may range from\0.1% in Asia to 43% in North Africa, even in apparently sporadic cases [2, 3] because of its low penetrance [4]. To date, this is the first screening of LRRK2 mutations in Ghana and only the third in a subSaharan African country [5, 6]. Fifty-four black African individuals meeting the UK Brain Bank criteria for PD were consecutively recruited between December 2008 and March 2011 from three outpatient clinics in Ghana. Every index case was reviewed by a neurologist specialized in movement disorders (R.C.). PD individuals were unrelated, with the exception of two sisters. At least one first-degree relative with tremors/possible PD has been reported in ten families (11 cases), suggesting a potential autosomal dominant (n = 7) or recessive (n = 3) pattern of inheritance. Control subjects (n = 46) had similar age and the same ethnicity as the cases, and no neurological disease or family history of tremors/PD (Table 1). Cases and controls were equally balanced among the three hospitals. The study was approved by the local ethics committee and all participants gave written consent before recruitment. Genomic DNA extraction was performed from saliva using the Oragene method (DNA Genotek, Ottawa, ON, Canada). The LRRK2 analysis was based on sequencing of exon41 (including G2019S and I2020T) and exon31 (including R1441G/C/H). LRRK2 exon41 and exon31 with their intron–exon boundaries were amplified by PCR using primers and condition previously reported [7]. Mutation analysis of the PCR purified product was performed by direct sequencing using the Big Dye Terminator Kit (version1.1, Applied Biosystems). Sequences were run on an ABI Prism 3130 XL Genetic Analyzer (PE Applied Biosystem) and the electropherograms analyzed with SeqScape software (Applied Biosystems). LRRK2 exon41 and exon31 screening did not reveal any mutation in cases and controls. We identified one heterozygous intron substitution IVS41 ? 30A [ G in a healthy subject and heterozygous IVS30-6C [ T in two PD and one healthy control. These variants have never been associated to a pathogenic mechanism and they are likely to be rare polymorphisms. Electronic supplementary material The online version of this article (doi:10.1007/s00415-011-6210-y) contains supplementary material, which is available to authorized users.