Frontotemporal dementia is a progressive neurodegenerative disorder with high clinical, genetic, and pathomorphological diversity It is the third most common cause of dementia in all ages and the most common cause of early onset dementia (below 65). Despite its multifactorial nature, up to 40% of patients have a family history where the autosomal dominant inheritance type is seen in a quarter of cases. In this review, we describe key genes whose mutations can result in the development of frontotemporal dementia, the possible pathogenic mechanisms of the degenerative process, and provide information on the clinical features of the disease for different genetic variants. Special emphasis is placed on the frontotemporal dementia phenotype that is associated with amyotrophic lateral sclerosis.