rs143484394

chr5-230886-C-T

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM1 PP3_Strong

The NM_004168.4(SDHA):c.781C>T(p.Arg261Cys) variant causes a missense change. The variant allele was found at a frequency of 0.00000616 in 1,461,834 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. R261H) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000062 (0 hom.)
• Consequence: SDHA NM_004168.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 5.59

Genes affected

SDHA (HGNC:10680): (succinate dehydrogenase complex flavoprotein subunit A) This gene encodes a major catalytic subunit of succinate-ubiquinone oxidoreductase, a complex of the mitochondrial respiratory chain. The complex is composed of four nuclear-encoded subunits and is localized in the mitochondrial inner membrane. Mutations in this gene have been associated with a form of mitochondrial respiratory chain deficiency known as Leigh Syndrome. A pseudogene has been identified on chromosome 3q29. Alternatively spliced transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Jun 2014]

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 16 uncertain in NM_004168.4
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.945

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SDHA	NM_004168.4	c.781C>T	p.Arg261Cys	missense_variant	7/15	ENST00000264932.11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SDHA	ENST00000264932.11	c.781C>T	p.Arg261Cys	missense_variant	7/15	1	NM_004168.4	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000796 AC: 2 AN: 251374 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135890

Gnomad AFR exome AF: 0.0000616

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.0000462

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000616 AC: 9 AN: 1461834 Hom.: 0 Cov.: 57 AF XY: 0.00000688 AC XY: 5 AN XY: 727222

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: 0.0000232

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000540

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 33

Bravo AF: 0.00000378

ESP6500AA AF: 0.000227 AC: 1

ESP6500EA AF: 0.00 AC: 0

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Paragangliomas 5;C5700310:Mitochondrial complex II deficiency, nuclear type 1 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Dec 08, 2023

This sequence change replaces arginine, which is basic and polar, with cysteine, which is neutral and slightly polar, at codon 261 of the SDHA protein (p.Arg261Cys). This variant is present in population databases (rs143484394, gnomAD 0.004%). This variant has not been reported in the literature in individuals affected with SDHA-related conditions. ClinVar contains an entry for this variant (Variation ID: 539677). 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) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on SDHA protein function. 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

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Aug 31, 2023

The p.R261C variant (also known as c.781C>T), located in coding exon 7 of the SDHA gene, results from a C to T substitution at nucleotide position 781. The arginine at codon 261 is replaced by cysteine, an amino acid with highly dissimilar 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	Pathogenic	0.95
BayesDel_addAF	Pathogenic	0.26	D
BayesDel_noAF	Uncertain	0.13
Cadd	Pathogenic	32
Dann	Uncertain	1.0
DEOGEN2	Uncertain	0.56	D;.;.
Eigen	Uncertain	0.50
Eigen_PC	Uncertain	0.34
FATHMM_MKL	Uncertain	0.86	D
LIST_S2	Uncertain	0.94	D;D;D
M_CAP	Uncertain	0.19	D
MetaRNN	Pathogenic	0.95	D;D;D
MetaSVM	Uncertain	0.18	D
MutationAssessor	Pathogenic	3.8	H;.;.
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Uncertain	0.78	T
PROVEAN	Pathogenic	-7.4	D;D;D
REVEL	Pathogenic	0.71
Sift	Pathogenic	0.0	D;D;D
Sift4G	Pathogenic	0.0	D;D;D
Polyphen		1.0	D;D;.
Vest4		0.93
MVP		0.88
MPC		1.5
ClinPred		1.0	D
GERP RS		3.1
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.87
gMVP		0.95

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: rs143484394; hg19: chr5-231001; COSMIC: COSV53765647; COSMIC: COSV53765647;