SS18L1 (HGNC:15592) was first reported in relation to autosomal dominant amyotrophic lateral sclerosis in 2013 (Chesi A et al., PMID: 23708140). SS18L1 encodes a calcium-responsive transactivator (CREST) that is an essential subunit of a neuron-specific chromatin-remodeling complex (nBAF). SS18L1 is expressed only in postmitotic neurons and regulates dendritic length. There are 5 variants (one nonsense, three missense, and one in-frame del) that have been reported in 5 probands in 3 publications (PMIDs: 23708140, 24360741, 31522742) that are included in this curation, one of which was not scored due to the patient harboring a variant in another ALS-causing gene and a high minor allele frequency in population databases. ALS-associated SS18L1 variants are suggested to dysregulate neuronal function by inhibiting dendrite outgrowth and microglial activation through a dominant-negative mechanism, however there is an absence of functional data from primary tissue of SS18L1 mutation carriers. This gene-disease relationship is also supported by experimental evidence (mouse models, expression, and protein interactions; PMIDs: 30976389, 14716005, 23708140). CREST knockout (Crest +/− ) and Q394X knock-in mice generated through CRISPR/Cas9 system displayed deficits in motor coordination and partially recapitulated ALS phenotypes (PMID: 30976389). In summary, there is limited evidence to support this gene-disease relationship. Although more evidence is needed to support a causal role, no convincing evidence has emerged that contradicts the gene-disease relationship. This classification was approved by the ClinGen ALS GCEP on the meeting date May 25, 2023 (SOP Version 9).
The GenCC data are available free of restriction under a CC0 1.0 Universal (CC0 1.0) Public Domain Dedication. The GenCC requests that you give attribution to GenCC and the contributing sources whenever possible and appropriate. The accepted Flagship manuscript is now available from Genetics in Medicine (https://www.gimjournal.org/article/S1098-3600(22)00746-8/fulltext).
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