Supplementary materials for Beneficial Microbes: <b>Causal relationship between </b><b><i>Faecalibacterium</i></b><b> abundance and risk of </b><b><i>Faecalibacterium</i></b><b>-related diseases: a two-sample bi-directional Mendelian randomisation st

<i>Faecalibacterium</i> is an essential probiotic in the human gut; changes in its abundance are associated with various disease states in many studies. However, the causal nature of such associations remains obscure. Therefore, we aimed to thoroughly investigate the causal relationships between <i>Faecalibacterium</i> and its related diseases. A two-sample bi-directional Mendelian randomization analysis was conducted using publicly available genome-wide association studies summary statistics for <i>Faecalibacterium</i> and its related diseases. We found that <i>Faecalibacterium</i> was negatively correlated with the risk of ankylosing spondylitis (odds ratio [OR]=0.526, 95% confidence interval [CI]:0.304-0.908, <i>P</i>=0.021), atopic dermatitis (OR=0.484, 95%CI: 0.261-0.898, <i>P</i>=0.021) and heart failure (OR=0.657, 95%CI: 0.467-0.924, <i>P</i>=0.016), while <i>Faecalibacterium</i> was positively associated with autism spectrum disorder risk (OR=2.529, 95%CI: 1.012-6.319, <i>P</i>=0.047). The results of reverse Mendelian randomization analysis showed that acute sinusitis (OR=0.902, 95%CI: 0.839-0.970, <i>P</i>=0.005) and Alzheimer's disease (OR=0.976, 95%CI: 0.958-0.993, <i>P</i>=0.008) was causally associated with lower <i>Faecalibacterium</i> abundance respectively, while cirrhosis (OR=1.154, 95%CI: 1.028-1.295, <i>P</i>=0.015) and multiple myeloma (OR=2.619×10¹², 95%CI: 2.492-2.754×10²⁴, <i>P</i>=0.043) was causally associated with higher <i>Faecalibacterium</i> abundance. Our findings firstly showed that changes in <i>Faecalibacterium</i> abundance may contribute to the risk of ankylosing spondylitis, atopic dermatitis, heart failure and autism spectrum disorders, and potentially as a result of acute sinusitis, Alzheimer's disease, cirrhosis and multiple myeloma.