1-17033069-A-G

Position:

• chr1-17033069-A-G

Variant summary

Our verdict is Pathogenic. Variant got 11 ACMG points: 11P and 0B. PM1 PM2 PM5 PP3_Strong PP5

The ENST00000375499.8(SDHB):​c.277T>C​(p.Cys93Arg) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. C93Y) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: SDHB ENST00000375499.8 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:5 U:1
• Conservation: PhyloP100: 8.19

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 Pathogenic. Variant got 11 ACMG points.

• PM1: In a hotspot region, there are 10 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 16 uncertain in ENST00000375499.8
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr1-17033068-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1796021.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.991
• PP5: Variant 1-17033069-A-G is Pathogenic according to our data. Variant chr1-17033069-A-G is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 165180.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=1, Pathogenic=2, Uncertain_significance=1}. Variant chr1-17033069-A-G is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SDHB	NM_003000.3	c.277T>C	p.Cys93Arg	missense_variant	3/8	ENST00000375499.8	NP_002991.2
SDHB	NM_001407361.1	c.277T>C	p.Cys93Arg	missense_variant	3/8		NP_001394290.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SDHB	ENST00000375499.8	c.277T>C	p.Cys93Arg	missense_variant	3/8	1	NM_003000.3	ENSP00000364649	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:5 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

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

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Nov 13, 2022

This variant is not present in population databases (gnomAD no frequency). This sequence change replaces cysteine, which is neutral and slightly polar, with arginine, which is basic and polar, at codon 93 of the SDHB protein (p.Cys93Arg). This missense change has been observed in individuals with paraganglioma and pheochromocytoma (PMID: 17848412, 19351833, 28374168, 31492822). For these reasons, this variant has been classified as Pathogenic. This variant disrupts the p.Cys93 amino acid residue in SDHB. Other variant(s) that disrupt this residue have been observed in individuals with SDHB-related conditions (PMID: 19258401, 27539324), which suggests that this may be a clinically significant amino acid residue. 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 expected to disrupt SDHB protein function. ClinVar contains an entry for this variant (Variation ID: 165180). -

not provided Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

CeGaT Center for Human Genetics Tuebingen

Oct 01, 2024

SDHB: PM1, PM2, PM5, PS4:Moderate, PP3 -

Paragangliomas 4 Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Myriad Genetics, Inc.

Apr 25, 2023

This variant is considered likely pathogenic. This variant has been reported in multiple individuals with clinical features of gene-specific disease [PMID: 17848412, 32971818, 28646318, 31492822]. This variant is expected to disrupt protein structure [Myriad internal data]. -

Hereditary cancer-predisposing syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Nov 14, 2019

The p.C93R pathogenic mutation (also known as c.277T>C), located in coding exon 3 of the SDHB gene, results from a T to C substitution at nucleotide position 277. The cysteine at codon 93 is replaced by arginine, an amino acid with highly dissimilar properties. This pathogenic variant has been identified in several individuals diagnosed with paragangliomas (Lima J et al. J. Clin. Endocrinol. Metab. 2007 Dec;92:4853-64; Neumann HP et al. Cancer Res. 2009 Apr;69:3650-6; Ambry internal data). Based on internal structural analysis, this variant is anticipated to result in loss of protein domain function (Inaoka DK et al. Int J Mol Sci. 2015 Jul;16(7):15287-308). Based on the supporting evidence, this alteration is interpreted as a disease-causing mutation. -

Hereditary pheochromocytoma-paraganglioma Pathogenic:1

Pathogenic, no assertion criteria provided

research

Section on Medical Neuroendocrinolgy, National Institutes of Health

-

- -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Aug 27, 2015

Variant classified as Uncertain Significance - Favor Pathogenic. The p.Cys93Arg variant in SDHB has been previously reported in 4 individuals with paraganglioma (Lima 2007, Neumann 2009, Sevilla 2009, Hermsen 2010) and 1 individual with phe ochromocytoma (LMM unpublished data). It was also identified in 2 reportedly un affected family members (Lima 2007), though this could be due to reduced penetra nce and/or age of onset. It was absent from large population studies. Computatio nal prediction tools and conservation analyses, including structural analyses, s uggest this variant may impact the protein, though this information is not predi ctive enough to determine pathogenicity. In summary, while there is some suspici on for a pathogenic role, the clinical significance of the Cys93Arg variant is u ncertain. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.58	D
BayesDel_noAF	Pathogenic	0.60
CADD	Pathogenic	30
DANN	Uncertain	0.98
DEOGEN2	Pathogenic	0.94	D;.;D
Eigen	Uncertain	0.58
Eigen_PC	Uncertain	0.37
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Benign	0.79	T;T;T
M_CAP	Pathogenic	0.48	D
MetaRNN	Pathogenic	0.99	D;D;D
MetaSVM	Pathogenic	0.98	D
MutationAssessor	Pathogenic	4.6	H;.;.
MutationTaster	Benign	1.0	D
PrimateAI	Pathogenic	0.89	D
PROVEAN	Pathogenic	-11	D;.;.
REVEL	Pathogenic	0.86
Sift	Pathogenic	0.0	D;.;.
Sift4G	Pathogenic	0.0	D;D;D
Polyphen		1.0	D;.;.
Vest4		0.99
MutPred		0.98		Gain of disorder (P = 0.0154);.;.;
MVP		0.95
MPC		0.94
ClinPred		1.0	D
GERP RS		3.3
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Varity_R		0.97
gMVP		0.97

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		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: rs727503415; hg19: chr1-17359564;