NM_003001.5:c.78-1G>T

Variant names:

• chr1-161328395-G-T
• rs786202200
• NM_003001.5:c.78-1G>T

Variant summary

Our verdict is Pathogenic. Variant got 14 ACMG points: 14P and 0B. PVS1_Strong PM2 PP5_Very_Strong

The NM_003001.5(SDHC):​c.78-1G>T variant causes a splice acceptor, intron change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: SDHC NM_003001.5 splice_acceptor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 6.95

Genes affected

SDHC (HGNC:10682): (succinate dehydrogenase complex subunit C) This gene encodes one of four nuclear-encoded subunits that comprise succinate dehydrogenase, also known as mitochondrial complex II, a key enzyme complex of the tricarboxylic acid cycle and aerobic respiratory chains of mitochondria. The encoded protein is one of two integral membrane proteins that anchor other subunits of the complex, which form the catalytic core, to the inner mitochondrial membrane. There are several related pseudogenes for this gene on different chromosomes. Mutations in this gene have been associated with paragangliomas. Alternatively spliced transcript variants have been described. [provided by RefSeq, May 2013]

ACMG classification

Verdict is Pathogenic. Variant got 14 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.2 fraction of the gene. No cryptic splice site detected. Exon removal is inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 1-161328395-G-T is Pathogenic according to our data. Variant chr1-161328395-G-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 534370.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SDHC	NM_003001.5	c.78-1G>T		splice_acceptor_variant, intron_variant	Intron 2 of 5	ENST00000367975.7	NP_002992.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SDHC	ENST00000367975.7	c.78-1G>T		splice_acceptor_variant, intron_variant	Intron 2 of 5	1	NM_003001.5	ENSP00000356953.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 29

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Gastrointestinal stromal tumor;C1854336:Paragangliomas 3 Pathogenic:1

Jan 15, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects an acceptor splice site in intron 2 of the SDHC gene. RNA analysis indicates that disruption of this splice site induces altered splicing and likely results in a shortened protein product. This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with SDHC-related conditions. ClinVar contains an entry for this variant (Variation ID: 534370). Studies have shown that disruption of this splice site results in skipping of skipping of exon 3, but is expected to preserve the integrity of the reading-frame (internal data). This variant disrupts a region of the SDHC protein in which other variant(s) (p.Arg50Cys) have been determined to be pathogenic (PMID: 19351833, 23175444, 23666964, 24102379). This suggests that this is a clinically significant region of the protein, and that variants that disrupt it are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic. -

Hereditary cancer-predisposing syndrome Pathogenic:1

Jul 17, 2023

Ambry Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.78-1G>T intronic variant results from a G to T substitution one nucleotide upstream from coding exon 3 of the SDHC gene. This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). This nucleotide position is highly conserved in available vertebrate species. In silico splice site analysis predicts that this alteration will weaken the native splice acceptor site. RNA studies have demonstrated that this alteration results in abnormal splicing in the set of samples tested (Ambry internal data). Alterations that disrupt the canonical splice site are expected to cause aberrant splicing, resulting in an abnormal protein or a transcript that is subject to nonsense-mediated mRNA decay. As such, this alteration is classified as likely pathogenic. -

Hereditary pheochromocytoma-paraganglioma Pathogenic:1

Apr 30, 2024

All of Us Research Program, National Institutes of Health

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant disrupts a canonical splice site and is predicted to result in abnormal splicing. Aberrant splicing and/or loss of function is an established disease mechanism. To date, this variant has not been reported in association with human disease in the medical literature. This variant is absent from large population databases, including the Genome Aggregation Database (http://gnomad.broadinstitute.org/). A different variant in this splice acceptor site (c.78-2A>G) has been previously reported in individuals with pheochromocytoma or paraganglioma (PMID: 18212813, 31666924). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.60	D
BayesDel_noAF	Pathogenic	0.32
CADD	Pathogenic	31
DANN	Uncertain	0.99
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.0
FATHMM_MKL	Uncertain	0.96	D
GERP RS		5.7

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.93
SpliceAI score (max)		0.97		Details are displayed if max score is > 0.2
DS_AL_spliceai		0.97		Position offset: 1

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs786202200; hg19: chr1-161298185;