rs202095022

chr1-17028647-T-C

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM1 PP3

The NM_003000.3(SDHB):c.376A>G(p.Lys126Glu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000118 in 1,614,056 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000012 (0 hom.)
• Consequence: SDHB NM_003000.3 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 7.33

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 3 ACMG points.

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 16 uncertain in NM_003000.3
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.745

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SDHB	NM_003000.3	c.376A>G	p.Lys126Glu	missense_variant	4/8	ENST00000375499.8
SDHB	NM_001407361.1	c.369+7A>G		splice_region_variant, intron_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SDHB	ENST00000375499.8	c.376A>G	p.Lys126Glu	missense_variant	4/8	1	NM_003000.3	P1

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152186 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.0000123 AC: 18 AN: 1461870 Hom.: 0 Cov.: 32 AF XY: 0.00000963 AC XY: 7 AN XY: 727240

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000135

Gnomad4 OTH exome AF: 0.0000497

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152186 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 74348

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000147

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000282 Hom.: 0

Bravo AF: 0.00000378

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

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Jun 23, 2023

This variant has not been reported in the literature in individuals affected with SDHB-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces lysine, which is basic and polar, with glutamic acid, which is acidic and polar, at codon 126 of the SDHB protein (p.Lys126Glu). ClinVar contains an entry for this variant (Variation ID: 574109). 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. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt SDHB protein function. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Feb 29, 2024

The p.K126E variant (also known as c.376A>G), located in coding exon 4 of the SDHB gene, results from an A to G substitution at nucleotide position 376. The lysine at codon 126 is replaced by glutamic acid, an amino acid with similar properties. This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. 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
AlphaMissense	Uncertain	0.44
BayesDel_addAF	Pathogenic	0.51	D
BayesDel_noAF	Pathogenic	0.50
Cadd	Pathogenic	28
Dann	Uncertain	1.0
DEOGEN2	Uncertain	0.79	D;.;T
Eigen	Uncertain	0.35
Eigen_PC	Uncertain	0.49
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.99	D;D;D
M_CAP	Uncertain	0.27	D
MetaRNN	Pathogenic	0.74	D;D;D
MetaSVM	Pathogenic	0.97	D
MutationAssessor	Uncertain	2.3	M;.;.
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.71	T
PROVEAN	Uncertain	-3.7	D;.;.
REVEL	Pathogenic	0.70
Sift	Uncertain	0.019	D;.;.
Sift4G	Benign	0.26	T;T;T
Polyphen		0.26	B;.;.
Vest4		0.88
MutPred		0.49		Loss of methylation at K126 (P = 0.0329);.;.;
MVP		0.94
MPC		0.31
ClinPred		0.93	D
GERP RS		6.2
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.79
gMVP		0.83

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.15		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: rs202095022; hg19: chr1-17355142;