Frontotemporal dementia [22 genes]

Between 5% and 15% of presenile dementias (<65 years) are of the frontotemporal type, with a prevalence of 10-15 per 100,000 in the 45-65 years group. Between 25% and 50% of patients with frontotemporal dementia present previous familial cases of dementia or psychiatric disease, and between 10% and 30% are consistent with an autosomal dominant inheritance pattern (Rohrer et al., 2009). Pathogenic variants in C9orf72, GRN, and MAPT are involved in 80% of these autosomal dominant forms. In the case of C9orf72, a single genetic alteration associated with amyotrophic lateral sclerosis (ALS) and/or frontotemporal dementia has been detected, consisting of a (GGGGCC) hexanucleotide expansion not detectable by NGS.

Dementia poses an important social, health, and economic problem. 25% of people older than 55 years of age have a family history of dementia. In 2016, it affected 46.8 million people worldwide. With an exponential growth, it is expected that this number will rise to 131.5 million by 2050 (World Alzheimer Report 2016).

Diagnosis, prognosis and genetic counseling in affected individuals and family members.