Notably, mutations in the LIR-motif proteins p62 (SQSTM1) and optineurin (OPTN) contribute to familial forms of frontotemporal dementia and amyotrophic lateral sclerosis.
The purpose of this study was to find mutations in the SQSTM1 gene encoding p62 in Japanese patients with amyotrophic lateral sclerosis (ALS), since this gene has been recently identified as a causative gene for familial and sporadic ALS in the United States.
The SQSTM1 gene analysis revealed the presence of a novel missense mutation (M401V) in exon 8 in one subject with a familial and aggressive form of PDB.
The most important causal gene for classical PDB is Sequestosome 1 (SQSTM1), which is a scaffold protein in the NF-kappaB signalling pathway, and mutations affecting the UBA (ubiquitin-associated) domain of this protein occur in between 20-50% of familial and 10-20% of sporadic PDB cases.
A positional cloning effort in French Canadian families with Paget's disease of bone (PDB) resulted in the identification of a mutation in the sequestosome1 (SQSTM1) gene in a subset of both familial and sporadic PDB cases.
We conclude that the G1181 allele of TNFRSF11B, encoding lysine at codon 3 of the OPG protein, predisposes to the development of sporadic PDB and familial PDB that is not caused by SQSTM1 mutations.
We conducted mutation screening of positional candidate genes in the PDB3 locus in patients with PDB, and also identified mutations in the gene encoding SQSTM1 as a common cause of familial and sporadic PDB.