Pathogenic effect of TP73 gene variants in people with amyotrophic lateral sclerosis

Objective: To identify novel disease associated loci for amyotrophic lateral sclerosis (ALS), we utilized sequencing data and performed in vitro and in vivo experiments to demonstrate pathogenicity of mutations identified in TP73.

Methods: We analyzed exome sequences of 87 sporadic ALS patients and 324 controls, with confirmatory sequencing in independent ALS cohorts of >2,800 patients.  For the top hit, TP73, a regulator of apoptosis, differentiation, and a binding partner as well as homolog of the tumor suppressor gene TP53, we assayed mutation effects using in vitro and in vivo experiments.  C2C12 myoblast differentiation assays, characterization of myotube appearance, and immunoprecipitation of p53-p73 complexes were perform in vitro.  In vivo, we used CRISPR/Cas9 targeting of zebrafish tp73 to assay motor neuron number and axon morphology.

Results: Four heterozygous rare, nonsynonymous mutations in TP73 were identified in our sporadic ALS cohort. In independent ALS cohorts...