1-17024007-C-G

Variant names:

• chr1-17024007-C-G
• rs1553177435
• NM_003000.3:c.608G>C

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM1 PM2

The NM_003000.3(SDHB):​c.608G>C​(p.Gly203Ala) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G203R) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 33)
• Consequence: SDHB NM_003000.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 2.63

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 4 ACMG points.

• PM1: In a hotspot region, there are 6 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 15 uncertain in NM_003000.3
• 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.608G>C	p.Gly203Ala	missense_variant	Exon 6 of 8	ENST00000375499.8	NP_002991.2
SDHB	NM_001407361.1	c.554G>C	p.Gly185Ala	missense_variant	Exon 6 of 8		NP_001394290.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SDHB	ENST00000375499.8	c.608G>C	p.Gly203Ala	missense_variant	Exon 6 of 8	1	NM_003000.3	ENSP00000364649.3
SDHB	ENST00000491274.6	c.566G>C	p.Gly189Ala	missense_variant	Exon 6 of 8	5		ENSP00000480482.2
SDHB	ENST00000463045.3	c.437G>C	p.Gly146Ala	missense_variant	Exon 6 of 8	3		ENSP00000481376.2
SDHB	ENST00000485515.5	n.542G>C		non_coding_transcript_exon_variant	Exon 6 of 7	5		ENSP00000519322.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

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

Feb 28, 2019

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces glycine with alanine at codon 203 of the SDHB protein (p.Gly203Ala). The glycine residue is moderately conserved and there is a small physicochemical difference between glycine and alanine. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals with SDHB-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.15
BayesDel_addAF	Pathogenic	0.16	D
BayesDel_noAF	Uncertain	0.0
CADD	Benign	19
DANN	Benign	0.97
DEOGEN2	Uncertain	0.70	D;.
Eigen	Benign	-0.20
Eigen_PC	Benign	-0.024
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Uncertain	0.92	D;D
M_CAP	Uncertain	0.19	D
MetaRNN	Uncertain	0.44	T;T
MetaSVM	Uncertain	0.72	D
MutationAssessor	Benign	1.5	L;.
PrimateAI	Pathogenic	0.85	D
PROVEAN	Benign	-1.6	N;.
REVEL	Uncertain	0.44
Sift	Benign	0.29	T;.
Sift4G	Benign	0.29	T;T
Polyphen		0.010	B;.
Vest4		0.40
MutPred		0.66		Loss of stability (P = 0.1051);.;
MVP		0.90
MPC		0.20
ClinPred		0.71	D
GERP RS		4.6
Varity_R		0.24
gMVP		0.83

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: rs1553177435; hg19: chr1-17350502;