Arg4810Lys mutation in RNF213 among Eastern Indian non-MMD ischemic stroke patients: a genotype-phenotype correlation.

INTRODUCTION: RNF213 mutations have been reported mostly in moyamoya disease (MMD) with varying frequencies across different ethnicities. However, its prevalence in non-MMD adult-onset ischemic stroke is still not well explored. AIMS AND OBJECTIVES: This present study thus aims to screen the most common RNF213 variant (Arg4810Lys, among East Asians) in the Eastern Indian non-MMD ischemic stroke patients and correlate it with long-term progression and prognosis of the patients. The subjects were analyzed for this variant using PCR-RFLP and confirmed using Sanger sequencing method. RESULT AND CONCLUSION: We have identified Arg4810Lys variant among eleven young-onset familial ischemic stroke patients in heterozygous manner. A positive correlation of the variant with positive family history (P = 0.001), earlier age at onset (P = 0.002), and history of recurrent stroke (P = 0.015) was observed. However, the carriers showed better cognitive performances in memory (P = 0.042) and executive function (P = 0.004). Therefore, we can conclude that Arg4810Lys/RNF213 - a pathogenic variant for young-onset familial ischemic stroke with higher incidence of recurrent events unlike in MMD cases, have no additional impact on cognition among Eastern Indians.

Genetic Variations and Altered Blood mRNA Level of Circadian Genes and BDNF as Risk Factors of Post-Stroke Cognitive Impairment Among Eastern Indians.

Post-stroke cognitive impairment (PSCI) is a clinical outcome in around 30% of post-stroke survivors. BDNF is a major gene in this regard. It is regulated by circadian rhythm. The circadian genes are correlated with stroke timings at molecular level. However, studies suggesting the role of these on susceptibility to PSCI are limited. We aim here to determine: (a) genetic risk variants in circadian clock genes, BDNF and (b) dysregulation in expression level of CLOCK, BMAL1, and BDNF that may be associated with PSCI. BDNF (rs6265G/A, rs56164415C/T), CLOCK (rs1801260T/C, rs4580704G/C), and CRY2 (rs2292912C/G) genes variants were genotyped among 119 post-stroke survivors and 292 controls from Eastern part of India. In addition, we analyzed their gene expression in Peripheral blood Mononuclear cells (PBMC) from 15 PSCI cases and 12 controls. The mRNA data for BDNF was further validated by its plasma level through ELISA (n = 38). Among the studied variants, only rs4580704/CLOCK showed an overall association with PSCI (P = 0.001) and lower Bengali Mini-Mental State Examination (BMSE) score. Its 'C' allele showed a correlation with attention deficiency. The language and memory impairments showed association with rs6265/BDNF, while the 'CC' genotype of rs2292912/CRY2 negatively influenced language and executive function. A significant decrease in gene expression for CLOCK and BDNF in PBMC (influenced by specific genotypes) of PSCI patients was observed than controls. Unlike Pro-BDNF, plasma-level mBDNF was also lower in them. Our results suggest the genetic variants in CLOCK, CRY2, and BDNF as risk factors for PSCI among eastern Indians. At the same time, a lowering expression of CLOCK and BDNF genes in PSCI patients than controls describes their transcriptional dysregulation as underlying mechanism for post-stroke cognitive decline.

An Indian Young-onset Dementia With Parkinsonism With Double Heterozygous Mutations in ABCA7 and PRKN Identified Through Whole-exome Sequencing.

Alzheimer disease and Parkinson disease dementia are the 2 most common neurodegenerative diseases have substantial overlap in pathologic, genetic, and clinical manifestation and complex in nature. Here, for the first time, we report an Indian female young patient who presented with clinical manifestation of both Alzheimer disease and Parkinsonism, including dystonia with rapid disease progression. We identified a heterozygous mutation in the ATP-binding cassette transporter A7 gene and double heterozygous mutation in PRKN by whole-exome sequencing. This case is an example of complex etiology of neurodegenerative disorders and highlights the importance of genetic tests, including whole-exome sequencing in complex diseases.

Identification of GBA mutations among neurodegenerative disease patients from eastern India.

INTRODUCTION: GBA mutations have been reported in PD, PDD and DLB - but not associated with cognitive impairment for example in PSP, AD or MSA. However, frequencies of GBA mutations are ethnicity dependent. The present study aims to identify commonly reported GBA mutations (mostly from Asia), among eastern Indian patients with neurodegenerative disorders. METHODS: The patient cohort consisting of 198 classical PD cases, 136 PD cases with cognitive impairment, 184 cases with Parkinson Plus syndrome, 46 AD and 241 unrelated controls, from eastern India. Subjects were analyzed for IVS2 + 1A > G, p.Arg120Trp, p.His255Gln, p.Arg257Gln, p.Glu326Lys, p.Asn370Ser, p.Asp409His, p.Leu444Pro, & RecNciI by PCR-RFLP techniques and confirmed by Sanger sequencing method. RESULTS: We have identified only p.Leu444Pro variant among nine cases; three PDD, one DLB, two PD, two PSP and one AD patients in heterozygous condition. The highest frequency for p.Leu444Pro variant was found among PDD subgroup (3.95 %, P = 0.0134). An overall significant overrepresentation of positive family history (P = 0.000049), impaired recent memory (P = 0.0123) was observed among p.Leu444Pro carriers. Further, subgroup analysis for PD, PD-MCI and PDD, revealed statistically significant higher frequency of early age at onset (P = 0.0455), positive family history (P = 0.0025), higher UPDRS III score (off state) (P = 0.006), advanced H&Y stage (P = 0.045) and anxious behaviour (P = 0.0124) among p.Leu444Pro positive patients. CONCLUSION: The p.Leu444Pro mutation of GBA was found in patients with PD, PDD, DLB, PSP and AD. An Overall higher frequency of positive family history and impaired recent memory are significantly associated with for p.Leu444Pro carriers from eastern India. Our study also ascertains contribution of p.Leu444Pro to an earlier onset of PD, PD-MCI and PDD, higher UPDRS III score (off state) against positive family history background. Furthermore, taking into consideration other Indian studies, we can conclude that p.Leu444Pro mutation plays a limited role in PD and other neurodegenerative disorders.

Role of LRRK2 variant p.Gly2019Ser in patients with Parkinsonism.

Background & objectives: Parkinsonian disorder, including Parkinson's disease (PD), is an aetiologically complex neurodegenerative disorder. Mutations in leucine-rich repeat kinase 2 (LRRK2) gene have been implicated in an autosomal dominant form of PD with variable penetrance. The identification of a common LRRK2 variant (p.Gly2019Ser) in dementia with Lewy bodies indicated its potential role in Parkinsonian disorder. The current study was aimed to identify the p.Gly2019Ser variant in Indian patients with Parkinsonian disorder. Methods: The patient group consisting of 412 classical PD patients, 107 PD patients with cognitive impairment, 107 patients with Parkinson plus syndrome and 200 unrelated controls were recruited from eastern part of India. The allele representing p.Gly2019Ser variant was screened by polymerase chain reaction followed by restriction fragment length polymorphism analysis. Results: The p.Gly2019Ser variant was identified in an East Indian young-onset female PD patient in a heterozygous state having several motor and autonomic problems without disturbed cognition. Her younger brother, sister and elder son harbouring the same mutation were asymptomatic carriers for the variant. However, the influence of DNM3 on decreased disease onset in this family was not clear. Interpretation & conclusions: Identification of the p.Gly2019Ser variant in only one patient among a large number of Indian patients (n=626) with Parkinsonian disorder in our study suggests a limited role of the LRRK2 variant towards disease pathogenesis.

Evaluation of FGF 20 variants for susceptibility to Parkinson's disease in Eastern Indians.

BACKGROUND: Parkinson's disease (PD) is the second most common neurodegenerative disease and has a complex etiology. Single nucleotide polymorphisms in the 3'-untranslated region of Fibroblast growth factor 20 (FGF 20) have been reported to be associated with PD; however, the results are controversial. Although FGF20 enhances the survival of dopaminergic neurons, it may also result in PD susceptibility by altering alpha-synuclein expression. MATERIALS AND METHODS: To identify and characterize genetic risk variants in FGF 20 in Eastern Indian PD patients, 2 SNPs of FGF 20 (rs1721100 and rs2720208) were genotyped in 336 PD cases and 313 ethnically matched controls by PCR-RFLP. RESULTS: We observed statistically significant differences in genotypic and allelic frequencies of rs1721100 between PD cases and controls but not for rs12720208. Haplotype G-C showed a significant protective effect against PD. A functional assay revealed that the risk allele C at rs1721100 has little or no effect on relative luciferase activity from a reporter construct in the presence of miR-3189-3p, whereas allele G results in significant dose-dependent reduction. CONCLUSION: Our results suggest that FGF 20 is a susceptibility gene for PD in Eastern Indians.