Background: Previous studies have shown a correlation between neurodegenerative diseases and cancers. However, the biological processes for these diseases are not completely known, and the genetic factors for their onset are not defined.

Methods: This study reports the genetic relationships of different neurodegenerative diseases, such as Multiple Sclerosis (MS), Alzheimer's Disease (AD), and Parkinson's disease (PD) and cancer types (squamous cell lung carcinoma, esophageal adenocarcinoma, and colorectal cancer), with other human traits, based on cross-trait Linkage Disequilibrium Score regression (LDSC). We then applied a clumping approach to select candidate genes for each disease, and via an miRNA analysis, we identified miRNAs that could regulate those genes.

Results: LDSC revealed an inverse association of human traits with neurodegenerative diseases and cancer. Indeed, the cancer types studied were positively correlated with "Body Mass Index (BMI)," while AD, PD, and MS showed a negative correlation. miR-1-3p, miR-34a-5p, and miR-27a-3p were revealed as common biomarkers among the different pathological conditions.

Conclusions: The present study suggests novel genetic associations between neurological diseases, cancer types and new targets to explain the genetic sharing between the diseases.