Genetic analysis has identified several genes and loci as underlying frontotemporal dementia (FTD). These include mutations in the granulin precursor gene (GRN, OMIM 138945)^1,2 and microtubule-associated protein tau gene (MAPT, OMIM 157140).³ Most recently, a hexanucleotide repeat expansion in the noncoding region of the chromosome 9 open reading frame 72 gene (C9ORF72, OMIM 614260) has been shown to be the genetic cause of disease in a group of patients with FTD.^4,5 Nonetheless, a large part of the genetic cause of FTD remains unknown. This is particularly evident in families with ages at onset between 55 and 70 years where mendelian variants in yet to be identified genes are thought to underlie the disease. Because of the low frequency of these variants, they will not be identifiable through genome-wide association studies. Technological advances now allow the analyses of complete exomes and genomes, placing us in a position to study these families. In fact, several recent studies have succeeded in identifying the genetic basis of different disorders by using exome and genome sequencing.^6-9 These studies demonstrate that even by using a small number of samples, it is now possible to uncover genetic alterations not only in mendelian diseases but also in multifactorial complex disorders. This has great clinical utility with major implications for disease gene discovery, diagnosis, and, ultimately, therapeutic approaches.

Identifying early-detection biomarkers have become an increasingly important approach in the treatment and prevention of Alzheimer's disease (AD). In this study, we investigated the potential of brain-derived neurotrophic factor (BDNF), complement fa

Triggering receptor expressed on myeloid cells 2 (TREM2) homozygous mutations cause Nasu-Hakola disease, an early-onset recessive form of dementia preceded by bone cysts and fractures. The same type of mutations has recently been shown to cause frontotemporal dementia (FTD) without the presence of any bone phenotype. Here, we further confirm the association of TREM2 mutations with FTD-like phenotypes by reporting the first compound heterozygous mutation in a Turkish family.