The SPTBN4 gene is located on chromosome 19 at 19q13.2 and encodes the spectrin beta, non-erythrocytic 4 protein, one of the spectrin family of proteins. The protein acts as a scaffold that links the actin cytoskeleton to the plasma membrane and is important for appropriate localization of specific membrane proteins, including ion channels in axons of neurons. SPTBN4 was first reported in relation to an autosomal recessive neurodevelopmental disorder in 2017 (Knierim et al., PMID: 28540413). Evidence supporting this gene-disease relationship includes case-level data and experimental data. At least 8 unique variants (nonsense, frameshift, splice site, and missense) in this gene that have been reported in at least 7 unrelated individuals in 4 publications (PMID: 28540413; Wang et al., 2018, PMID: 29861105; Hausler et al., 2019, PMID: 31857255) have been included in this curation. Segregation with disease was seen in at least one additional family member in two families (PMID: 29861105; PMID: 31857255). At least seven unique variants have been reported, which are predicted to result in a truncated or abnormal gene product. Loss of function appears to be the mechanism of disease. Although missense variants have been reported, their role in the disorder remains less clear. This gene-disease relationship is supported by multiple mouse and piglet models that recapitulate the human phenotype, displaying hypotonia, tremors, neuropathy, myopathy, and central hearing loss (Derks et al., 2019, PMID: 31850074; Parkinson et al., 2001, PMID: 11528393). Expression is enriched in nervous system and consistent with the neuronal/neuromuscular pathology observed in patients and animal models, with high expression in neurons and enrichment in nodes of Ranvier and axon initial segment (Berghs et al., 2000; PMID: 11086001). In summary, there is definitive evidence to support the relationship between SPTBN4 and autosomal recessive neurodevelopmental disorder with hypotonia, neuropathy, and deafness. This classification was approved by the ClinGen Syndromic Disorders Gene Curation Expert Panel on the meeting date 12.01.2021 (SOP Version 8).
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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