1-17024077-G-C

Variant names:

• chr1-17024077-G-C
• NM_003000.3:c.541-3C>G

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2 PP3_Strong

The NM_003000.3(SDHB):​c.541-3C>G variant causes a splice region, intron change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency: Genomes: not found (cov: 33)
• Consequence: SDHB NM_003000.3 splice_region, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 2.29

Genes affected

SDHB (HGNC:10681): (succinate dehydrogenase complex iron sulfur subunit B) This tumor suppressor gene encodes the iron-sulfur protein subunit of the succinate dehydrogenase (SDH) enzyme complex which plays a critical role in mitochondria. The SDH enzyme complex is composed of four nuclear-encoded subunits. This enzyme complex converts succinate to fumarate which releases electrons as part of the citric acid cycle, and the enzyme complex additionally provides an attachment site for released electrons to be transferred to the oxidative phosphorylation pathway. The SDH enzyme complex plays a role in oxygen-related gene regulation through its conversion of succinate, which is an oxygen sensor that stabilizes the hypoxia-inducible factor 1 (HIF1) transcription factor. Sporadic and familial mutations in this gene result in paragangliomas, pheochromocytoma, and gastrointestinal stromal tumors, supporting a link between mitochondrial dysfunction and tumorigenesis. Mutations in this gene are also implicated in nuclear type 4 mitochondrial complex II deficiency. [provided by RefSeq, Jun 2022]

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SDHB	NM_003000.3	c.541-3C>G		splice_region_variant, intron_variant	Intron 5 of 7	ENST00000375499.8	NP_002991.2
SDHB	NM_001407361.1	c.487-3C>G		splice_region_variant, intron_variant	Intron 5 of 7		NP_001394290.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SDHB	ENST00000375499.8	c.541-3C>G		splice_region_variant, intron_variant	Intron 5 of 7	1	NM_003000.3	ENSP00000364649.3
SDHB	ENST00000491274.6	c.499-3C>G		splice_region_variant, intron_variant	Intron 5 of 7	5		ENSP00000480482.2
SDHB	ENST00000463045.3	c.370-3C>G		splice_region_variant, intron_variant	Intron 5 of 7	3		ENSP00000481376.2
SDHB	ENST00000485515.5	n.475-3C>G		splice_region_variant, intron_variant	Intron 5 of 6	5		ENSP00000519322.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 29

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Pheochromocytoma;C0238198:Gastrointestinal stromal tumor;C1861848:Paragangliomas 4 Uncertain:1

Jul 21, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Studies have shown that this variant is associated with altered splicing resulting in unknown protein product impact (Invitae). This variant has been observed in individual(s) with autosomal dominant paraganglioma-pheochromocytoma syndromes (Invitae). This variant is not present in population databases (gnomAD no frequency). This sequence change falls in intron 5 of the SDHB gene. It does not directly change the encoded amino acid sequence of the SDHB protein. It affects a nucleotide within the consensus splice site. -

Hereditary cancer-predisposing syndrome Uncertain:1

Apr 15, 2022

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.541-3C>G intronic variant results from a C to G substitution 3 nucleotides upstream from coding exon 6 in the SDHB gene. This nucleotide position is well conserved in available vertebrate species. In silico splice site analysis predicts that this alteration will weaken the native splice acceptor site and will result in the creation or strengthening of a novel splice acceptor site. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.23
CADD	Uncertain	25
DANN	Benign	0.93

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.97
SpliceAI score (max)		0.96		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.96		Position offset: -1
DS_AL_spliceai		0.81		Position offset: -3

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

Publications

No publications associated with this variant yet.

Other links and lift over

hg19: chr1-17350572;