rs1332910409

Variant names:

• chr1-161340635-C-T
• rs1332910409
• NM_003001.5:c.221C>T

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 6P and 4B. PM1 PP3_Strong BS2

The NM_003001.5(SDHC):​c.221C>T​(p.Thr74Ile) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000093 in 1,613,736 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 (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. T74A) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000096 (0 hom.)
• Consequence: SDHC NM_003001.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 2.04
• Publications: 0 publications found

Genes affected

SDHC (HGNC:10682): (succinate dehydrogenase complex subunit C) This gene encodes one of four nuclear-encoded subunits that comprise succinate dehydrogenase, also known as mitochondrial complex II, a key enzyme complex of the tricarboxylic acid cycle and aerobic respiratory chains of mitochondria. The encoded protein is one of two integral membrane proteins that anchor other subunits of the complex, which form the catalytic core, to the inner mitochondrial membrane. There are several related pseudogenes for this gene on different chromosomes. Mutations in this gene have been associated with paragangliomas. Alternatively spliced transcript variants have been described. [provided by RefSeq, May 2013]

SDHC Gene-Disease associations (from GenCC):

• hereditary pheochromocytoma-paraganglioma

  Inheritance: AD Classification: DEFINITIVE, SUPPORTIVE Submitted by: Orphanet, ClinGen
• pheochromocytoma/paraganglioma syndrome 3

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: G2P, Labcorp Genetics (formerly Invitae), Ambry Genetics
• Carney-Stratakis syndrome

  Inheritance: AD Classification: STRONG, SUPPORTIVE Submitted by: Orphanet, Genomics England PanelApp
• gastrointestinal stromal tumor

  Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae), Genomics England PanelApp
• renal cell carcinoma

  Inheritance: AD Classification: MODERATE Submitted by: Genomics England PanelApp
• Cowden disease

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• mitochondrial disease

  Inheritance: Unknown Classification: NO_KNOWN Submitted by: ClinGen

ACMG classification

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

• PM1: In a hotspot region, there are 7 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 26 uncertain in NM_003001.5
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.946
• BS2: High AC in GnomAdExome4 at 14 Unknown,AD gene.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_003001.5. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SDHC	NM_003001.5	MANE Select	c.221C>T	p.Thr74Ile	missense	Exon 4 of 6	NP_002992.1
	SDHC	NM_001407115.1		c.341C>T	p.Thr114Ile	missense	Exon 5 of 7	NP_001394044.1
	SDHC	NM_001035511.3		c.221C>T	p.Thr74Ile	missense	Exon 4 of 5	NP_001030588.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SDHC	ENST00000367975.7	TSL:1 MANE Select	c.221C>T	p.Thr74Ile	missense	Exon 4 of 6	ENSP00000356953.3
	SDHC	ENST00000342751.8	TSL:1	c.221C>T	p.Thr74Ile	missense	Exon 4 of 5	ENSP00000356952.3
	SDHC	ENST00000432287.6	TSL:1	c.119C>T	p.Thr40Ile	missense	Exon 3 of 5	ENSP00000390558.2

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152168 Hom.: 0 Cov.: 32

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: 0.00000958 AC: 14 AN: 1461568 Hom.: 0 Cov.: 31 AF XY: 0.0000124 AC XY: 9 AN XY: 727114

African (AFR) AF: 0.00 AC: 0 AN: 33474

American (AMR) AF: 0.00 AC: 0 AN: 44720

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26132

East Asian (EAS) AF: 0.00 AC: 0 AN: 39694

South Asian (SAS) AF: 0.00 AC: 0 AN: 86254

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53394

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 0.0000117 AC: 13 AN: 1111764

Other (OTH) AF: 0.0000166 AC: 1 AN: 60370

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152168 Hom.: 0 Cov.: 32 AF XY: 0.0000135 AC XY: 1 AN XY: 74334

African (AFR) AF: 0.00 AC: 0 AN: 41438

American (AMR) AF: 0.00 AC: 0 AN: 15278

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3470

East Asian (EAS) AF: 0.00 AC: 0 AN: 5196

South Asian (SAS) AF: 0.00 AC: 0 AN: 4832

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10594

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.0000147 AC: 1 AN: 68038

Other (OTH) AF: 0.00 AC: 0 AN: 2094

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000756

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:1

Jul 28, 2022

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Has not been previously published as pathogenic or benign to our knowledge

Hereditary cancer-predisposing syndrome Uncertain:1

Dec 03, 2024

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.T74I variant (also known as c.221C>T), located in coding exon 4 of the SDHC gene, results from a C to T substitution at nucleotide position 221. The threonine at codon 74 is replaced by isoleucine, an amino acid with similar properties. This amino acid position is well 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.

Gastrointestinal stromal tumor;C1854336:Pheochromocytoma/paraganglioma syndrome 3 Uncertain:1

Mar 12, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces threonine, which is neutral and polar, with isoleucine, which is neutral and non-polar, at codon 74 of the SDHC protein (p.Thr74Ile). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with SDHC-related conditions. ClinVar contains an entry for this variant (Variation ID: 465964). 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 SDHC protein function with a positive predictive value of 80%. 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 v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.94
BayesDel_addAF	Pathogenic	0.35	D
BayesDel_noAF	Pathogenic	0.26
CADD	Uncertain	25
DANN	Pathogenic	1.0
DEOGEN2	Uncertain	0.72	D
Eigen	Pathogenic	0.70
Eigen_PC	Uncertain	0.57
FATHMM_MKL	Uncertain	0.81	D
LIST_S2	Uncertain	0.93	D
M_CAP	Uncertain	0.18	D
MetaRNN	Pathogenic	0.95	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	4.5	H
PhyloP100		2.0
PrimateAI	Uncertain	0.56	T
PROVEAN	Pathogenic	-5.3	D
REVEL	Pathogenic	0.91
Sift	Uncertain	0.0010	D
Sift4G	Pathogenic	0.0010	D
Polyphen		1.0	D
Vest4		0.77
MutPred		0.85		Loss of methylation at R72 (P = 0.0517)
MVP		0.99
MPC		1.1
ClinPred		1.0	D
GERP RS		4.1
Varity_R		0.92
gMVP		0.96
Mutation Taster		=53/47	polymorphism

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

Other links and lift over

dbSNP: rs1332910409; hg19: chr1-161310425;