ClinVar Genomic variation as it relates to human health

This variant is expected to severely impact normal RNA splicing, and consequently, protein structure and/or function. The frequency of this variant in the general population is consistent with pathogenicity (http://gnomad.broadinstitute.org). In multiple individuals, including cases of Miyoshi myopathy and limb girdle muscular dystrophy, this variant has been seen with a single recessive pathogenic variant in the same gene, suggesting this variant may also be pathogenic. This variant is also referred to as c.2697+1G>A and c.3016+1G>A in published literature. Assessment of experimental evidence suggests this variant results in abnormal protein function. This variant has been shown to cause exon skipping (PMID: 25312915).

Canonical splice site variant expected to result in aberrant splicing, although in the absence of functional evidence the actual effect of this sequence change is unknown.; Published minigene assays show that this canonical splice variant results in the skipping of exon 25, suggesting that it results in abnormal splicing (Kergourlay et al., 2014); This variant is associated with the following publications: (PMID: 22246893, 25525159, 23243261, 12796534, 11532985, 18853459, 29382405, 31980526, 31589614, 33610434, 24438169, 25312915)

This sequence change affects a donor splice site in intron 25 of the DYSF gene. RNA analysis indicates that disruption of this splice site induces altered splicing and likely results in a shortened protein product. This variant is present in population databases (rs140108514, gnomAD 0.2%). Disruption of this splice site has been observed in individuals with autosomal recessive limb-girdle muscular dystrophy and Miyoshi myopathy (PMID: 12796534, 18853459, 21816046, 22246893, 23243261, 27854218). This variant is also known as G3016+1A and c.3016+1G>A. ClinVar contains an entry for this variant (Variation ID: 94291). Studies have shown that disruption of this splice site results in skipping of exon 25, but is expected to preserve the integrity of the reading-frame (PMID: 25312915). For these reasons, this variant has been classified as Pathogenic.

The heterozygous c.2697+1G>A variant in DYSF was identified by our study in one individual in the compound heterozygous state, with another pathogenic variant, in one individual with limb-girdle muscular dystrophy (LGMD). This variant has been identified in 0.1706% (41/24026) of African chromosomes in the Genome Aggregation Database (gnomAD, http://gnomad.broadinstitute.org; dbSNP rs140108514). Although this variant has been seen in the general population, its frequency is not high enough to rule out a pathogenic role. The c.2697+1G>A variant in DYSF has been reported in 3 individuals with LGMD (PMID: 23243261). The presence of this variant in combination with reported pathogenic variants and in 2 individuals with LGMD increases the likelihood that the c.2697+1G>A variant is pathogenic. In vitro functional studies provide some evidence that the c.2697+1G>A variant may impact protein function by causing abnormal splicing of Exon 25 (PMID: 25312915). However, these types of assays may not accurately represent biological function.This variant occurs in the invariant region (+/- 1/2) of the splice consensus sequence and is predicted to cause altered splicing leading to an in-frame transcript deletion and abnormal or absent protein. Loss of function In the DYSF gene is an established disease mechanism in autosomal recessive LGMD. In summary, the clinical significance of the 2697+1G>A variant is pathogenic. ACMG/AMP Criteria applied: PVS1_Moderate, PS3, PM3_Strong (Richards 2015).

PM2, PS4_moderate, PVS1

NM_003494.3(DYSF):c.2643+1G>A is a canonical splice variant classified as pathogenic in the context of dysferlinopathy. c.2643+1G>A has been observed in cases with relevant disease (PMID: 30564623, 12796534, 23243261, 27854218, 18832576, 24488599, 21816046). Functional assessments of this variant are available in the literature (PMID: 25312915). c.2643+1G>A has been observed in population frequency databases (gnomAD: AFR 0.13%). In summary, NM_003494.3(DYSF):c.2643+1G>A is a canonical splice variant in a gene where loss of function is a known mechanism of disease, is predicted to disrupt protein function, and has been observed more frequently in cases with the relevant disease than in healthy populations. Please note: this variant was assessed in the context of healthy population screening.

The DYSF c.2643+1G>A variant is predicted to disrupt the GT donor site and interfere with normal splicing. This variant has been reported in the homozygous or compound heterozygous state in patients diagnosed with limb-girdle muscular dystrophy type 2B (LGMD2B) or Miyoshi myopathy (Krahn et al. 2009. PubMed ID: 18853459; Takahashi et al. 2013. PubMed ID: 23243261). In a mini-gene assay, the c.2643+1G>A variant led to exon skipping (Kergourlay et al. 2014. PubMed ID: 25312915). This variant has been reported at an allele frequency of ~0.2% in an African population; in other ethnicities it is absent or reported less frequently (i.e. <0.01%) (http://gnomad.broadinstitute.org/variant/2-71795213-G-A). Variants that disrupt the consensus splice donor site in DYSF are expected to be pathogenic. This variant is interpreted as pathogenic.