Major depressive disorder (MDD) is characterized as clinical depression, which primarily affects the mood and behaviour of an individual. In the present study butyrylcholinesterase (BChE), a co-regulatory cholinergic neurotransmitter enzyme implicated in several putative neuronal and non-neuronal physiological roles was investigated for its role in MDD. Eighty MDD patients and sixty-one healthy controls were recruited for the study. BChE activity was measured by Ellman’s method using serum while DNA samples of the patients were genotyped for BCHE polymorphisms rs3495 (c.*189G > A) and rs1803274 (c.1699G > A) by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and tetra-primer Amplification Refractory Mutation System- polymerase chain reaction (ARMS-PCR). The genotyping was further validated by Sanger Sequencing. Biochemical estimation of serum BChE levels revealed a statistically significant decrease of enzyme activity in MDD patients (69.96) as compared to healthy controls (90.97), which was independent of age and gender. BCHE single nucleotide polymorphism rs1803274 genotype GA was found to be associated with the disease under a dominant model (OR 2.32; 95% CI 1.09–4.96; p value = 0.025). Furthermore, risk allele-A frequency was higher in cases (p value = 0.013) than control. Carriers of rs1803274 GA genotype showed reduced mean BChE activity than wild-type allele GG homozygotes (p value = 0.040). Gender-based analysis revealed a protective role of rs3495 in females (χ² = 6.87, p value = 0.032, RM: OR 0.173, CI = 0.043–0.699 (p value = 0.017). In addition, rs1803274 risk allele-A was observed to be significantly higher in males (χ² = 4.258, p value = 0.039). In conclusion, the present study is indicative of a role of BChE in the pathophysiology of MDD where genetic polymorphisms were observed to effect BChE activity. Further replication studies in different ethnicities are recommended to validate the current observations.

重度抑郁症（MDD）的特点是临床抑郁症，主要影响个体的情绪和行为。在本研究中，丁酰胆碱酯酶 (BChE) 是一种参与多种推定的神经元和非神经元生理作用的共同调节胆碱能神经递质酶，研究了其在 MDD 中的作用。该研究招募了 80 名 MDD 患者和 61 名健康对照者。BChE 活性通过 Ellman 方法使用血清测量，同时对患者的 DNA 样本进行BCHE基因分型多态性 rs3495 (c.*189G > A) 和 rs1803274 (c.1699G > A) 通过聚合酶链反应-限制性片段长度多态性 (PCR-RFLP) 和四引物扩增难治性突变系统-聚合酶链反应 (ARMS-PCR) . Sanger测序进一步验证了基因分型。血清 BChE 水平的生化评估显示，与健康对照组 (90.97) 相比，MDD 患者 (69.96) 的酶活性显着降低，这与年龄和性别无关。BCHE单核苷酸多态性 rs1803274 基因型 GA 被发现与显性模型下的疾病相关（OR 2.32；95% CI 1.09-4.96；p值 = 0.025）。此外，风险等位基因 A 频率在病例 ( p值 = 0.013) 比控制。rs1803274 GA基因型携带者的平均BChE活性低于野生型等位基因GG纯合子（p值= 0.040）。基于性别的分析显示 rs3495 在女性中具有保护作用（^χ2 =  6.87，p值 = 0.032，RM：OR 0.173，CI = 0.043-0.699（p值 = 0.017）。此外，观察到 rs1803274 风险等位基因-A男性显着更高 ( χ ²  = 4.258, p值 = 0.039）。总之，本研究表明 BChE 在 MDD 的病理生理学中的作用，其中观察到遗传多态性影响 BChE 活性。建议在不同种族进行进一步的复制研究以验证当前的观察结果。