Novel ABCD1 and MTHFSD Variants in Taiwanese Bipolar Disorder: A Genetic Association Study

Background and Objectives: In recent years, bipolar disorder (BD), a multifaceted mood disorder marked by severe episodic mood fluctuations, has been shown to have an impact on disability-adjusted life years (DALYs). The increasing prevalence of BD highlights the need for better diagnostic tools, particularly those involving genetic insights. Genetic association studies can play a crucial role in identifying variations linked to BD, shedding light on its genetic underpinnings and potential therapeutic targets. This study aimed to identify novel genetic variants associated with BD in the Taiwanese Han population and to elucidate their potential roles in disease pathogenesis. Materials and Methods: Genotyping was conducted using the Taiwan Precision Medicine Array (TPM Array) on 128 BD patients and 26,122 control subjects. Following quality control, 280,177 single nucleotide polymorphisms (SNPs) were analyzed via chi-square tests, and linkage disequilibrium (LD) analyses were employed to examine the associations among key SNPs. Results: Eleven SNPs reached significance (p < 10^-5), with the variant rs11156606 in the ABCD1 gene-implicated in fatty acid metabolism-emerging as a prominent finding. LD analysis revealed that rs11156606 is strongly linked with rs73640819, located in the 3' untranslated region, suggesting a regulatory role in gene expression. Additionally, rs3829533 in the MTHFSD gene was found to be in strong LD with the missense variants rs3751800 and rs3751801, indicating potential alterations in protein function. Conclusion: These findings enhance the genetic understanding of BD within a Taiwanese cohort by identifying novel risk-associated variants and support the potential for using these markers in early diagnosis and targeted therapeutic strategies.