Early-Onset Alzheimer’s Disease, APOE4 And C9orf72 Expansion: A Case Report

Neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease, and frontotemporal dementia (FTD) have become a focus of concern at the socio-sanitary and economic level due to their exponential growth as life expectancy for humans has increased through the years. Research into the genetic basis underlying the diseases should allow for earlier diagnosis, better prognosis and the possibility of discovering new therapeutic targets. In this article, we describe the case of a 45-year-old patient who presented with early-onset dementia with symptoms similar to AD, for which he was diagnosed. However, his genetic study revealed a mutation in C9orf72, a gene associated with FTD and amyotrophic lateral sclerosis. In addition, the patient is a heterozygous carrier of APOE c.338T>C (E4 allele), considered a risk factor for AD. This finding would suggest an involvement of C9orf72 in triggering AD.