Two different mechanisms may account for this phenomenon: first, miRNA response might be directly or indirectly linked to the mutant protein expression (e.g., ATXN1 in spinocerebellar ataxia type 1 and APP in Alzheimer's disease), or second, a result of a general transcriptional deregulation in the affected tissues. This evidence concerns the gene APP and early-onset autosomal dominant Alzheimer disease.