1-17053949-T-G

Variant names:

• chr1-17053949-T-G
• rs878854580
• NM_003000.3:c.71A>C

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

The NM_003000.3(SDHB):​c.71A>C​(p.Gln24Pro) variant causes a missense, splice region change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 3/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Uncertain significance (★★). Another nucleotide change resulting in the same amino acid substitution has been previously reported as Uncertain significance in ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. Q24H) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 31)
• Consequence: SDHB NM_003000.3 missense, splice_region
• Scores: Splicing: ADA: 0.8511
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 1.27

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 Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SDHB	NM_003000.3	c.71A>C	p.Gln24Pro	missense_variant, splice_region_variant	Exon 1 of 8	ENST00000375499.8	NP_002991.2
SDHB	NM_001407361.1	c.71A>C	p.Gln24Pro	missense_variant, splice_region_variant	Exon 1 of 8		NP_001394290.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SDHB	ENST00000375499.8	c.71A>C	p.Gln24Pro	missense_variant, splice_region_variant	Exon 1 of 8	1	NM_003000.3	ENSP00000364649.3
SDHB	ENST00000466613.2	n.83A>C		splice_region_variant, non_coding_transcript_exon_variant	Exon 1 of 3	2
SDHB	ENST00000485515.5	n.59A>C		splice_region_variant, non_coding_transcript_exon_variant	Exon 1 of 7	5		ENSP00000519322.1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 31

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

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

Dec 06, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces glutamine, which is neutral and polar, with proline, which is neutral and non-polar, at codon 24 of the SDHB protein (p.Gln24Pro). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with SDHB-related conditions. ClinVar contains an entry for this variant (Variation ID: 239439). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be tolerated. 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. -

Hereditary cancer-predisposing syndrome Uncertain:1

Dec 11, 2022

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.Q24P variant (also known as c.71A>C), located in coding exon 1 of the SDHB gene, results from an A to C substitution at nucleotide position 71. The glutamine at codon 24 is replaced by proline, an amino acid with similar properties. This amino acid position is conserved. In addition, the in silico prediction for this alteration is inconclusive. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Hereditary pheochromocytoma-paraganglioma Uncertain:1

Jan 03, 2024

All of Us Research Program, National Institutes of Health

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This missense variant replaces glutamine with proline at codon 24 of the SDHB protein. Computational prediction is inconclusive regarding the impact of this variant on protein structure and function (internally defined REVEL score threshold 0.5 < inconclusive < 0.7, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has not been reported in individuals affected with SDHB-related disorders in the literature. This variant has not been identified in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.067
BayesDel_addAF	Pathogenic	0.22	D
BayesDel_noAF	Uncertain	0.070
CADD	Benign	23
DANN	Benign	0.95
DEOGEN2	Uncertain	0.42	T
Eigen	Benign	-0.38
Eigen_PC	Benign	-0.18
FATHMM_MKL	Benign	0.46	N
LIST_S2	Benign	0.66	T
M_CAP	Pathogenic	0.62	D
MetaRNN	Uncertain	0.70	D
MetaSVM	Uncertain	0.53	D
MutationAssessor	Benign	0.0	N
PrimateAI	Uncertain	0.52	T
PROVEAN	Benign	-1.6	N
REVEL	Uncertain	0.57
Sift	Benign	0.30	T
Sift4G	Benign	0.36	T
Polyphen		0.0	B
Vest4		0.53
MutPred		0.48		Gain of loop (P = 0.0013);
MVP		0.81
MPC		0.23
ClinPred		0.32	T
GERP RS		4.0
Varity_R		0.49
gMVP		0.52

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.85
dbscSNV1_RF	Benign	0.67
SpliceAI score (max)		0.010		Details are displayed if max score is > 0.2

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

Publications

LitVar

Other links and lift over

dbSNP: rs878854580; hg19: chr1-17380444;