Resequencing the complete SNCA locus in Indian patients with Parkinson's disease.

The genetic loci implicated in familial Parkinson's disease (PD) have limited generalizability to the Indian PD population. We tested mutations and the frequency of known mutations in the SNCA gene in a PD cohort from India. We selected 298 PD cases and 301 age-matched controls for targeted resequencing (before QC), along with 363 PD genomes of Indian ancestry and 1029 publicly available whole genomes from India as healthy controls (IndiGenomes), to determine the frequency of monogenic SNCA mutations. The raw sequence reads were analyzed using an in-house analysis pipeline, allowing the detection of small variants and structural variants using Manta. The in-depth analysis of the SNCA locus did not identify missense or structural variants, including previously identified SNCA mutations, in the Indian population. The familial forms of SNCA gene variants do not play a major role in the Indian PD population and this warrants further research in the under-represented population.

Deep Brain Stimulation for Parkinson's Disease-the Developing World's Perspective.

Background: Deep brain stimulation (DBS) is the most widely used device-assisted therapy in patients with moderately advanced stages of Parkinson's disease (PD) experiencing motor complications. Only a minority of eligible patients get the opportunity to undergo DBS in the developing world. Objectives: To examine the proportion and characteristics of patients with motor complications of PD who are willing for DBS and who undergo surgery. Methods: Patients with motor complications of PD eligible for DBS over a five-year study period (2016-2020) were included. The demographic, clinical and socio-economic characteristics and information on their status in 2021 were collected and analyzed. Results: Among 1017 patients, 223 had motor symptoms qualifying for DBS and follow-up information available. Only 78 (35%) opted for surgery. The willing patients had higher socioeconomic status, were older and had longer duration of PD and motor complications, more freezing of gait, cognitive symptoms, and neuropsychiatric disturbances. 37 of them were found unfit during pre-operative work-up; only 41 (18%) with motor complications were finally taken up for DBS. Age, duration or severity of motor symptoms did not differ between patients who were finally selected for surgery and those who were not. Conclusions: Less than one-fifth of our patients with motor complications of PD finally underwent DBS. The patients appeared to wait till the late stages of PD, before making a decision on availing surgical treatment. The delay resulted in nearly half of them being found unfit in pre-operative work-up. Our findings may enable clinicians to counsel eligible patients more efficiently.

Whole exome and targeted gene sequencing to detect pathogenic recessive variants in early onset cerebellar ataxia.

Over 100 genetically distinct causal known loci for hereditary ataxia phenotype poses a challenge for diagnostic work-up for ataxia patients in a clinically relevant time and precision. In the present study using next-generation sequencing, we have investigated pathogenic variants in early-onset cerebellar ataxia cases using whole exome sequencing in singleton/family-designed and targeted gene-panel sequencing. A total of 98 index patients were clinically and genetically (whole exome sequencing (WES) in 16 patients and targeted gene panel of 41 ataxia causing genes in 82 patients) evaluated. Four families underwent WES in family based design. Overall, we have identified 24 variants comprising 20 pathogenic and four likely-pathogenic both rare/novel, variations in 21 early onset cerebellar ataxia patients. Among the identified variations, SACS (n = 7) and SETX (n = 6) were frequent, while ATM (n = 2), TTPA (n = 2) and other rare loci were observed. We have prioritized novel pathogenic variants in RARS2 and FA2H loci through family based design in two out of four families.