A historic example of L1-conferred disease is Haemophilia A, which is caused by insertional mutagenesis. There are nearly 100 examples of known diseases caused by retroelement insertions, including some types of cancer and neurological disorders. Correlation between L1 mobilization and oncogenesis has been reported for epithelial cell cancer (carcinoma). Hypomethylation of LINES is associated with chromosomal instability and altered gene expression and is found in various cancer cell types in various tissues types. Hypomethylation of a specific L1 located in the MET onco gene is associated with bladder cancer tumorogenesis, Shift work sleep disorder is associated with increased cancer risk because light exposure at night reduces melatonin, a hormone that has been shown to reduce L1-induced genome instability.