Mutation Analysis of NOS1 Exon 18 Polymorphisms with the Risk of Parkinson’s Disease: A Cross-sectional Study

Introduction: Nitric Oxide Synthase 1 (NOS1) has been implicated in Parkinson’s Disease (PD) pathogenesis through its role in neuronal signaling and oxidative stress. However, evidence of specific genetic contributions in Indian populations remains limited. Aim: The present study aimed to examine whether genetic variations in exon 18 of the NOS1 gene are associated with PD in a South Indian cohort. Materials and Methods: The present observational crosssectional study was conducted between March 2022 and May 2023 at a Tertiary Care Hospital, Karnataka, India. One hundred clinically diagnosed PD patients underwent detailed neurological assessment and 1 mL venous blood collection. Deoxyribonucleic Acid (DNA) was extracted and exon 18 of NOS1 (chromosome no 12 ) was amplified by PCR and sequenced using Sanger sequencing. Variants were analysed and verified using bioinformatics tools and reference sequences. Results: The cohort comprised 65 males and 35 females, with 64 cases classified as sporadic, 34 idiopathic, and 2 familial. Demographic data showed that 67% were urban residents. Sequencing of exon 18 detected a synonymous single nucleotide variant (g.119313C>T, rs1047735) in three patients: two heterozygous and one homozygous. This variant (c.2706C>T) results in p.His902=, without amino acid change. Conclusion: Only synonymous variants were found. Although these variants do not change the amino acid sequence, they may influence NOS1 regulation at the RNA level. Larger casecontrol studies with functional analyses and broader genomic approaches such as whole-exome sequencing are necessary to clarify whether NOS1 exon 18 variants contribute to PD susceptibility.