Our results identify a novel pathogenic <i>SQSTM1</i> S224X mutation in an atypical FTD patient accompanied with loss of SQSTM1/p62 protein expression probably due to <i>SQSTM1</i> gene haploinsufficiency.
An FTD-linked p62D329G polymorphism and a rare D329H variant could not be proteolyzed by caspase-8, and these noncleavable variants failed to activate mTORC1, thereby revealing the detrimental effect of these mutations.
In this work the role of p62 in energy metabolism was studied in fibroblasts from FTD patients carrying two independent pathogenic mutations in the p62 gene, and in a p62-knock-down (p62 KD) human dopaminergic neuroblastoma cell line (SH-SY5Y).
We performed a systematic review on 42 pathological studies to assess the pooled prevalence rates and density (a measure of the number of inclusions per brain region) of (phosphorylated)-TDP-43, p62 and DRP neuronal inclusions in seven brain regions and the spinal cord of 261 C9ORF72-positive patients with amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD) and ALS-FTD.
A combination of whole-exome sequencing, Sanger sequencing and fragment analysis/Southern blot was performed in order to identify pathogenic mutations and novel variants in these genes as well as other FTD-related genes such as the 'charged multivesicular body protein 2B' (CHMP2B), the 'FUS RNA binding protein' (FUS), the 'TAR DNA binding protein' (TARDBP), the 'sequestosome1' (SQSTM1), and the 'valosin containing protein' (VCP).
Similar to mutations in VCP, dominantly inherited mutations in SQSTM1 are now associated with rimmed vacuolar myopathy, Paget disease of bone, amyotrophic lateral sclerosis, and frontotemporal dementia.