In this condition, protein deposits of Alpha-synuclein called lewy bodies develop in nerve cells in brain regions involved in memory, reasoning, perception, thinking, behavior and movement. Many people with DLB experience movement symptoms such as hunched posture, rigid muscles, shuffling walk and trouble initiating movement. Lewy body dementia is the second most common kind of dementia after Alzheimer’s disease that gradually causes decline in mental ability. It may sometimes causes visual hallucination and unusual behaviors such as having conversations with deceased loved ones. It sometimes exists in pure form, or with other brain changes, including those commonly observed in Alzheimer's and Parkinson's diseases.
A novel locus for DLB has been identified in Belgian families. A genome-wide scan and subsequent fine mapping of candidate loci revealed the locus linkage to 2q35-q36 adjacent to the previously reported PARK11 locus. Screening five candidate genes has not identified the disease-causing mutation. Further analysis of AD and PD causative genes in patients with DLB has been performed showing copy number variants in APP, SNCA and PARK2 genes. However, as the clinical diagnosis of DLB remains difficult, whether current genes associated with either AD or PD pathology influence all aspects of DLB or more particularly some overlapping pathology, remains to be determined. Due to poor sensitivity of the clinical diagnosis of DLB, identification of genes causing DLB requires autopsy-confirmation, rendering such studies difficult. Genetic analysis on further families with multiple autopsies is currently the only way for breakthroughs in the genetics of DLB.