Summary Background Frontotemporal dementia (FTD) is a complex disorder characterised by a broad range of clinical manifestations, differential pathological signatures, and genetic variability. Mutations in three genes—MAPT, GRN, and C9orf72—have been associated with FTD. We sought to identify novel genetic risk loci associated with the disorder. Methods We did a two-stage genome-wide association study on clinical FTD, analysing samples from 3526 patients with FTD and 9402 healthy controls. All participants had European ancestry. In the discovery phase (samples from 2154 patients with FTD and 4308 controls), we did separate association analyses for each FTD subtype (behavioural variant FTD, semantic dementia, progressive non-fluent aphasia, and FTD overlapping with motor neuron disease [FTD-MND]), followed by a meta-analysis of the entire dataset. We carried forward replication of the novel suggestive loci in an independent sample series (samples from 1372 patients and 5094 controls) and then did joint phase and brain expression and methylation quantitative trait loci analyses for the associated (p<5 × 10−8) and suggestive single-nucleotide polymorphisms. Findings We identified novel associations exceeding the genome-wide significance threshold (p<5 × 10−8) that encompassed the HLA locus at 6p21.3 in the entire cohort. We also identified a potential novel locus at 11q14, encompassing RAB38/CTSC, for the behavioural FTD subtype. Analysis of expression and methylation quantitative trait loci data suggested that these loci might affect expression and methylation incis. Interpretation Our findings suggest that immune system processes (link to 6p21.3) and possibly lysosomal and autophagy pathways (link to 11q14) are potentially involved in FTD. Our findings need to be replicated to better define the association of the newly identified loci with disease and possibly to shed light on the pathomechanisms contributing to FTD. Funding The National Institute of Neurological Disorders and Stroke and National Institute on Aging, the Wellcome/ MRC Centre on Parkinson’s disease, Alzheimer’s Research UK, and Texas Tech University Health Sciences Center.

Objective: To determine the frequency of a hexanucleotide repeat expansion in C9ORF72, a gene of unknown function implicated in frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS), in Australian FTD patient cohorts and to examine the clinical and neuropathologic phenotypes associated with this expansion. Methods:We examined a clinically ascertained FTD cohort (n ϭ 89) and a neuropathologically ascertained cohort of frontotemporal lobar degeneration cases with TDP-43 pathology (FTLD-TDP) (n ϭ 22) for the C9ORF72 hexanucleotide repeat expansion using a repeat primed PCR assay. All expansion-positive patients were genotyped for rs3849942, a surrogate marker for the chromosome 9p21 risk haplotype previously associated with FTD and ALS. Results:The C9ORF72 repeat expansion was detected in 10% of patients in the clinically diagnosed cohort, rising to 29% in those with a positive family history of early-onset dementia or ALS. The prevalence of psychotic features was significantly higher in expansion-positive cases (56% vs 14%). In the pathology cohort, 41% of TDP-43-positive cases harbored the repeat expansion, and all exhibited type B pathology. One of the 17 expansion-positive probands was homozygous for the "nonrisk" G allele of rs3849942. Conclusions:The C9ORF72 repeat expansion is a relatively common cause of FTD in Australian populations, and is especially common in those with FTD-ALS, psychotic features, and a strong family history. Detection of a repeat expansion on the 9p21 putative "nonrisk" haplotype suggests that not all mutation carriers are necessarily descended from a common founder and indicates that the expansion may have occurred on multiple haplotype backgrounds. Neurology Frontotemporal dementia (FTD) refers to a heterogeneous group of diseases characterized by personality changes, behavioral or language deficits associated with progressive loss of neurons in the frontal and temporal regions of the brain, and a range of pathologies characterized by the accumulation of intraneuronal protein inclusions. [1][2][3] Evidence for the overlap between FTD and amyotrophic lateral sclerosis (ALS) has been strengthened by the recent finding of a hexanucleotide repeat expansion in C9ORF72, a gene of unknown function on chromosome 9p21, in Finnish and North American familial FTD and ALS cohorts. 4,5 It remains unclear, however, how common this repeat expansion is in different populations, and what clinical and pathologic phenotypes are associated with this mutation. We examined the frequency of this repeat expansion in a well-characterized Australian FTD cohort according to the strength of From Neuroscience

IMPORTANCE Abnormal eating behaviors are common in patients with frontotemporal dementia (FTD), yet their exact prevalence, severity, and underlying biological mechanisms are not understood. OBJECTIVE To define the severity of abnormal eating behavior and sucrose preference and their neural correlates in patients with behavioral variant FTD (bvFTD) and semantic dementia. DESIGN, SETTING, AND PARTICIPANTS Forty-nine patients with dementia (19 with bvFTD, 15 with semantic dementia, and 15 with Alzheimer disease) were recruited, and their eating behavior was compared with that of 25 healthy controls. The study was conducted from

IntroductionThe genetics underlying posterior cortical atrophy (PCA), typically a rare variant of Alzheimer's disease (AD), remain uncertain.MethodsWe genotyped 302 PCA patients from 11 centers, calculated risk at 24 loci for AD/DLB and performed an exploratory genome-wide association study.ResultsWe confirm that variation in/near APOE/TOMM40 (P = 6 × 10−14) alters PCA risk, but with smaller effect than for typical AD (PCA: odds ratio [OR] = 2.03, typical AD: OR = 2.83, P = .0007). We found evidence for risk in/near CR1 (P = 7 × 10−4), ABCA7 (P = .02) and BIN1 (P = .04). ORs at variants near INPP5D and NME8 did not overlap between PCA and typical AD. Exploratory genome-wide association studies confirmed APOE and identified three novel loci: rs76854344 near CNTNAP5 (P = 8 × 10−10 OR = 1.9 [1.5–2.3]); rs72907046 near FAM46A (P = 1 × 10−9 OR = 3.2 [2.1–4.9]); and rs2525776 near SEMA3C (P = 1 × 10−8, OR = 3.3 [2.1–5.1]).DiscussionWe provide evidence for genetic risk factors specifically related to PCA. We identify three candidate loci that, if replicated, may provide insights into selective vulnerability and phenotypic diversity in AD.