Autosomal-recessive early-onset parkinsonism is clinically and genetically heterogeneous. The genetic causes of approximately 50% of autosomal-recessive early-onset forms of Parkinson disease (PD) remain to be elucidated. Homozygozity mapping and exome sequencing in 62 isolated individuals with early-onset parkinsonism and confirmed consanguinity followed by data mining in the exomes of 1,348 PD-affected individuals identified, in three isolated subjects, homozygous or compound heterozygous truncating mutations in vacuolar protein sorting 13C (VPS13C). VPS13C mutations are associated with a distinct form of early-onset parkinsonism characterized by rapid and severe disease progression and early cognitive decline; the pathological features were striking and reminiscent of diffuse Lewy body disease. In cell models, VPS13C partly localized to the outer membrane of mitochondria. Silencing of VPS13C was associated with lower mitochondrial membrane potential, mitochondrial fragmentation, increased respiration rates, exacerbated PINK1/Parkin-dependent mitophagy, and transcriptional upregulation of PARK2 in response to mitochondrial damage. This work suggests that loss of function of VPS13C is a cause of autosomal-recessive early-onset parkinsonism with a distinctive phenotype of rapid and severe progression.

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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 factor H (CFH), tumor necrosis factor-α (TNFα), interleukin 10 (IL-10), and heat shock protein 90 (Hsp90) as serum biomarkers for AD in a cohort of the Turkish population because they have been suggested to be associated with AD. Serum BDNF, CFH, TNFα, IL-10, and Hsp90 levels in three groups of patients, early-onset AD (EOAD; age of onset < 65; n = 22), late-onset AD (LOAD; age of onset > 65; n = 54), and mild cognitive impairment (MCI) (n = 30), were compared with age-matched healthy controls (age < 65, n = 18 and age > 65; n = 32) using ELISA. The serum BDNF levels significantly decreased and TNFα levels significantly increased in the EOAD and LOAD groups compared to the age-matched healthy controls. There was a correlation between serum TNFα and IL-10 levels in the LOAD and healthy control groups. Serum CFH levels in the LOAD and MCI patients were significantly decreased compared with controls. Serum Hsp90 levels in the EOAD, LOAD, and MCI patients were significantly decreased compared with controls. The protein misfolding, the inflammatory response, and decreased neurotrophic factor synthesis are all suggested to be related to AD type brain pathology, and our results indicate these alterations might be traced from serum samples. For accurate early diagnosis of AD, it is important to determine a profile of alterations in multiple biomarkers in large-scale population studies.

No abstract

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.