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Abstract Background A new locus for amyotrophic lateral sclerosis – frontotemporal dementia (ALS-FTD) has recently been ascribed to chromosome 9p. Methods We identified chromosome 9p segregating haplotypes within two families with ALS-FTD (F476 and F2) and undertook mutational screening of candidate genes within this locus. Results Candidate gene sequencing at this locus revealed the presence of a disease segregating stop mutation (Q342X) in the intraflagellar transport 74 (IFT74) gene in family 476 (F476), but no mutation was detected within IFT74 in family 2 (F2). While neither family was sufficiently informative to definitively implicate or exclude IFT74 mutations as a cause of chromosome 9-linked ALS-FTD, the nature of the mutation observed within F476 (predicted to truncate the protein by 258 amino acids) led us to sequence the open reading frame of this gene in a large number of ALS and FTD cases (n = 420). An additional sequence variant (G58D) was found in a case of sporadic semantic dementia. I55L sequence variants were found in three other unrelated affected individuals, but this was also found in a single individual among 800 Human Diversity Gene Panel samples. Conclusion Confirmation of the pathogenicity of IFT74 sequence variants will require screening of other chromosome 9p-linked families.

Mutations in the hypoxia-inducible factor angiogenin (ANG) have been identified in Amyotrophic Lateral Sclerosis (ALS) patients, but the potential role of ANG in ALS pathogenesis was undetermined. Here we show that angiogenin promotes motoneuron survival both in vitro and in vivo. Angiogenin protected cultured motoneurons against excitotoxic injury in a PI-3-kinase/Akt kinase-dependent manner, whereas knock-down of angiogenin potentiated excitotoxic motoneuron death. Expression of wild-typeANG protected against endoplasmic reticulum (ER) stress-induced and trophic-factor-withdrawal-induced cell death in vitro, whereas the ALS-associated ANG mutant K40I exerted no protective activity and failed to activate Akt-1. In SOD1G93A mice angiogenin delivery increased lifespan and motoneuron survival, restored the disease-associated decrease in Akt-1 survival signaling, and reversed a pathophysiological increase in ICAM-1 expression. Our data demonstrate that angiogenin is a key factor in the control of motoneuron survival. [ABSTRACT FROM AUTHOR]

Background: A new locus for amyotrophic lateral sclerosis - frontotemporal dementia (ALS-FTD) has recently been ascribed to chromosome 9p. Methods: We identified chromosome 9p segregating haplotypes within two families with ALS-FTD (F476 and F2) and undertook mutational screening of candidate genes within this locus. Results: Candidate gene sequencing at this locus revealed the presence of a disease segregating stop mutation (Q342X) in the intraflagellar transport 74 (IFT74) gene in family 476 (F476), but no mutation was detected within IFT74 in family 2 (F2). While neither family was sufficiently informative to definitively implicate or exclude IFT74 mutations as a cause of chromosome 9-linked ALS-FTD, the nature of the mutation observed within F476 (predicted to truncate the protein by 258 amino acids) led us to sequence the open reading frame of this gene in a large number of ALS and FTD cases (n = 420). An additional sequence variant (G58D) was found in a case of sporadic semantic dementia. I55L sequence variants were found in three other unrelated affected individuals, but this was also found in a single individual among 800 Human Diversity Gene Panel samples. Conclusion: Confirmation of the pathogenicity of IFT74 sequence variants will require screening of other chromosome 9p-linked families. [ABSTRACT FROM AUTHOR]