Shyla T. Govindappa

Absence/rarity of commonly reported LRRK2 mutations in Indian Parkinson's disease patients

Recent discovery of pathogenic mutations in the leucine-rich repeat kinase 2 (LRRK2) gene in Parkinsons disease (PD) patients in different ethnic groups have raised a hope of diagnostic screening and genetic counseling. We investigated the six most commonly reported mutations in LRRK2 gene among Indian PD patients, using PCR-RFLP method. Mutations G2019S, R1441C, R1441G, and R1441H were screened in 1012 individuals (PD, 800; controls, 212) while mutations I2012T and I2020T were screened in 748 PD patients. We did not observe any of these six mutations in this study sample except in a single female young onset PD patient who showed a heterozygous G2019S mutation. The absence of mutations was reconfirmed by sequencing of probands from several autosomal dominant PD families. Our observations suggest that these mutations may be a rare cause of PD among Indians and therefore of little help for diagnostic screening and genetic counseling for Indian PD patients.

VPS35 and EIF4G1 mutations are rare in Parkinson's disease among Indians

Mutations in 2 genes, vacuolar protein sorting homolog 35 (VPS35) and eukaryotic translation initiation factor 4 gamma 1 (EIF4G1), have been recently reported as causal in autosomal dominant Parkinsons disease (PD) among Caucasians. Their contribution to PD in other ethnic groups remains limited with 1% of VPS35 mutations observed in Caucasian and Japanese populations, but none in Chinese, and 11.57% of EIF4G1 mutations in Caucasian families and 0.09% and 0.17% in Caucasian and Chinese sporadic cases, respectively. We investigated the contribution, if any, of these 2 genes to familial and sporadic PD among the ethnically distinct Indian population. Complete exonic regions of these 2 genes were resequenced in 15 well-characterized PD families; the reported p.Asp620Asn in VPS35 and p.Arg1205His in EIF4G1 mutations were screened in an additional 54 familial and 251 sporadic PD cases, and no mutations were observed. These results, together with our previous reports on the absence of mutations in SNCA and LRRK2, warrant a continuing search for novel causative genes for PD among Indians.

Direct Costs of Managing Parkinson's Disease in India: Concerns in a Developing Country

Medicines and surgical interventions improve the quality of life of Parkinsons disease (PD) patients. These are still expensive options and are unaffordable to those living in developing countries. Managing PD in Indians who have a low annual gross national income (GNI; US

Role of polymorphisms in dopamine synthesis and metabolism genes and association of DBH haplotypes with Parkinson's disease among North Indians.

450–540) and for whom only a few (3%) have health insurance is a challenge. We interviewed 175 consecutive PD patients regarding health insurance and money spent for treatment. The annual income of nearly half the patients was less than rupees 50,000 (US

Evidence of mutations in RIC3 acetylcholine receptor chaperone as a novel cause of autosomal-dominant Parkinson's disease with non-motor phenotypes

1,148.63). Patients in this study spend nearly 16% to 41.7% of the average Indian GNI to buy medicines. Costs of treating PD in India are lower than those in developed nations but are still out of reach for most Indian patients.

Leads from xenobiotic metabolism genes for Parkinson’s disease among north Indians

Objectives Genetic and non-genetic components are believed to govern the etiology of common complex traits such as Parkinsons disease (PD). In view of the biochemical evidence of depleted dopamine levels in the affected brains and also the most common and effective therapeutic modality of administration of levodopa in PD, genes from the dopaminergic pathway emerge as major determinants. We have earlier shown the role of DRD4-120 bp duplication marker in PD susceptibility. In this study, contribution of six genes involved in dopamine synthesis and metabolism to PD susceptibility and disease severity was assessed in a North Indian PD cohort. Methods 339 patients diagnosed using UKPD brain bank criteria and 344 matched controls were recruited and disease severity was assessed using the Hoehn and Yahr scale and Unified Parkinson Disease Rating Scale III scores. Allelic, genotypic and haplotypic associations with PD were computed; severity was compared among the genotypic categories of markers; gene–gene interactions were assessed using multiple logistic regression. Results A highly significant association of dopamine β-hydroxylase (DBH) haplotypes (rs1611115T>C − rs1108580A>G − rs5320A>G − rs129882C>T) with PD was observed; haplotypes C-A-G-C [P=0.000005, Odds ratio (95% confidence interval): OR (95% CI)=1.76 (1.38–2.25)] and C-A-G-T [P=0.000001, OR (95% CI)=0.49 (0.37–0.65)] retaining significance after Bonferroni correction. rs129882, a 3′UTR SNP in DBH showed significant association with disease severity [Hoehn and Yahr (P=0.005) and Unified Parkinson Disease Rating Scale (P=0.006)]. Conclusion Observed association of DBH SNP/SNP haplotypes with PD susceptibility and its role in modulating disease severity reiterates the importance of dopamine pathway in sporadic PD etiology in general and potential therapeutic implications of DBH in particular.

The Indian turban trick : A novel sensory trick in blepharospasm

Background The known genetic determinants of Parkinsons disease (PD) do not explain all cases investigated to date. Contemporary sequencing technologies hold promise for enhanced causal variant discovery. We attempted to identify the putative causal variant in an Indian PD family by whole exome sequencing (WES). Methods WES data generated for two affected cousins from a 14-member PD family with some non-motor phenotypes were analysed. Variants prioritised were checked for segregation with disease by targeted sequencing. An independent PD cohort (n=280) was screened for additional mutations in the prioritised gene. Variants were functionally validated in PC12 cells differentiated into neurons. Results A heterozygous mutation c.169C>A, p.P57T in RIC3 acetylcholine receptor chaperone (11p15) segregated with disease in the family confirming an autosomal-dominant mode of inheritance. Another heterozygous mutation c.502G>C, p.V168L was detected in an unrelated PD case. Both mutations were absent in 144 healthy control and in 74 non-PD WES data available in-house and in 186 age and sex-matched controls screened by PCR sequencing. RIC3 is a known chaperone of neuronal nicotinic acetylcholine receptor subunit α-7 (CHRNA7). Dominant negative effect of RIC3 mutants in transfected PC12 cells was reflected by the reduced levels of endogenous CHRNA7 in the membrane fractions in western blots and lower colocalisation profiles in confocal micrographs. Conclusion The novel demonstration of a chaperone-mediated receptor density alteration due to RIC3 mutants provides strong evidence for the role of cholinergic pathway for the first time in PD aetiology. This may also be insightful for some non-motor symptoms and personalised treatment.

Exome Sequencing Identifies a Novel Homozygous Missense ATP13A2 Mutation

Objective Pesticide/neurotoxin/free radical-induced oxidative stress leading to dopaminergic neuronal vulnerability is known to promote sporadic Parkinson’s disease (PD). This study investigated the contribution of polymorphisms in genes from drug-metabolizing enzymes (DMEs) and the oxidative stress pathway to PD susceptibility and severity among a north Indian cohort. Methods Three hundred and thirty-nine PD patients diagnosed using UK PD brain bank criteria and 344 age-, sex-, and ethnicity-matched controls were recruited. Univariate and multivariate analyses were carried out to test allelic, genotypic, and haplotypic associations, and gene–gene interactions were assessed for 18 polymorphisms from 13 genes. Disease severity was calculated on the basis of the Hoehn and Yahr (HY) scale and Unified Parkinsons Disease Rating Scale III scores and was compared among the genotypic categories of markers. Results An association of GSTO1-rs4925 (P=0.04) and NQO1-rs1800566 (P=0.02) in univariate and multivariate analysis (P=0.01 and P=0.03, respectively) with disease susceptibility was observed. Significant and novel association of PON2-rs7493 (P=0.00009 with UPDRS III, P=0.003 with HY) with disease severity was retained after Bonferroni correction. On categorizing the cohort into young-onset PD (YOPD, n=90 cases, 104 controls) and late-onset PD ( n=249 cases, 240 controls), the association of several single nucleotide polymorphisms (SNPs) in DMEs was observed with YOPD. Conclusions The association of NQO1, PON2, and DME genes (this study) and NAT2 (previous study) with PD among Indians may point toward an inherent population-specific genetic predisposition. This, probably compounded by an increase in environmental toxins and the indiscriminate use of pesticides in our country in the last few decades, may suggest likely gene–environment interactions, which may explain the increasing incidence of YOPD among Indians.

Parkin mutations in familial and sporadic Parkinson's disease among Indians

Blepharospasm is a focal dystonia characterized by involuntary eyelid closure.1 Sensory tricks are sensory stimuli used by patients with dystonia to transiently reduce spasms. Herein we describe a patient of blepharospasm who used an Indian turban as a sensory trick. A 41-year-old forest guard presented with a 2-year history of upper limb tremors and nonprogressive involuntary closure of both eyes. Initially he had difficulty opening his eyes but since the past 18 months he noticed that merely touching his upper eyebrows would help him open his eyes (Segment 1). At his work, he was required to wear a cap resembling a baseball cap and he observed that the blepharospasm improved by 25% when the cap covered his eyebrows (Segment 2). He accidentally realized that when he wore a turban at home it was easier for him to open his eyes without having to touch his eyebrows (sensory trick). The trick of touching his right supraorbital ridge improved his blepharospasm by 30% after which he could write and read (Segment 3). Interestingly, he had no improvement on touching his left supraorbital ridge. At baseline, he rated the severity of his blepharospasm using the Visual analogue scale (VAS) as “10 ” and this improved after wearing a turban to “6. ” On the verbal scale he reported that his symptoms were “severe ” without a turban and they were “mild” after wearing a turban. He had no exposure to neuroleptics. His extraocular muscle movements were normal. He had left sided bradykinesia, rigidity, and rest tremors, and we diagnosed him as Parkinson’s disease (Hoehn and Yahr Stage1). The mechanism of sensory tricks in blepharospasm is unknown. In some patients applying contact over the specific site can transiently reduce the intensity of the spasms and so that they can carry on with their tasks with less interference from the unwanted muscular activity.2 Furthermore, studies have shown that the stimulus intensity modifies the blink reflex recovery rate in humans.3 Animals models to explain the focal dystonia have shown that the dysfunctional sensorimotor integration in which the nervous system misinterprets sensory signals or misinterprets the desired movement.4 Patients who used a sensory trick had a normal prepulse inhibition while those who did not had no such inhibition suggesting that abnormalities in sensory gating mechanism are a consequence rather than a cause for the dystonia.5 This is further strengthened by the fact that in some patients sensory gating mechanisms are likely amenable to adaptation and learning. The effective modulation of the sensory gating perhaps causes reorganization in the neuronal reflex circuits. Our Patient used the Indian turban, an everyday headgear, as an effective sensory trick, highlighting the fact that sensory gating mechanisms are perhaps amenable to adaptation and learning.

Genetic susceptibility to Parkinson’s disease among South and North Indians: I. Role of polymorphisms in dopamine receptor and transporter genes and association of DRD4 120-bp duplication marker

Kufor-Rakeb syndrome (KRS) (Mendelian Inheritance in Man no. 606693) is an autosomal recessive, juvenile parkinsonism caused by mutations in the ATP13A2 (adenosine 50-triphosphatase [ATPase] type 13A2) gene. The clinical features comprise akinetic rigid parkinsonism, dementia, psychosis, supranuclear gaze palsy, oculogyric dystonic spasms, facial-faucial-finger minimyoclonus, and spasticity. The disease is rare, and only a few patients have been reported to date. Whole exome sequencing is an emerging tool in the screening for mutations in several diseases in a timely and cost-effective manner. We describe a patient with KRS in whom we used exome sequencing and homozygosity mapping to identify a novel, homozygous missense mutation in ATP13A2.