rs772928706

Variant names:

• chr11-61438102-A-G
• rs772928706
• NM_017841.4:c.359A>G

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM1 PM2 PP3_Moderate

The NM_017841.4(SDHAF2):​c.359A>G​(p.Tyr120Cys) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,459,200 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. Y120H) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: SDHAF2 NM_017841.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:4
• Conservation: PhyloP100: 8.47
• Publications: 0 publications found

Genes affected

SDHAF2 (HGNC:26034): (succinate dehydrogenase complex assembly factor 2) This gene encodes a mitochondrial assembly factor needed for the flavination of a succinate dehydrogenase complex subunit (SDHA), which is required for activity of the succinate dehydrogenase complex. Mutations in this gene are associated with paraganglioma. [provided by RefSeq, May 2022]

SDHAF2 Gene-Disease associations (from GenCC):

• hereditary pheochromocytoma-paraganglioma

  Inheritance: AD Classification: DEFINITIVE, SUPPORTIVE Submitted by: Orphanet, ClinGen
• pheochromocytoma/paraganglioma syndrome 2

  Inheritance: AD Classification: DEFINITIVE, STRONG, MODERATE Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae), G2P

ENSG00000256591 (HGNC:):

ACMG classification

Our verdict: Likely_pathogenic. The variant received 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, 25 uncertain in NM_017841.4
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.902

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SDHAF2	NM_017841.4	c.359A>G	p.Tyr120Cys	missense_variant	Exon 3 of 4	ENST00000301761.7	NP_060311.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SDHAF2	ENST00000301761.7	c.359A>G	p.Tyr120Cys	missense_variant	Exon 3 of 4	1	NM_017841.4	ENSP00000301761.3
ENSG00000256591	ENST00000541135.5	c.359A>G	p.Tyr120Cys	missense_variant	Exon 3 of 5	4		ENSP00000443130.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1459200 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 726170

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33410

American (AMR) AF: 0.0000224 AC: 1 AN: 44720

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26106

East Asian (EAS) AF: 0.00 AC: 0 AN: 39688

South Asian (SAS) AF: 0.00 AC: 0 AN: 86184

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53420

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

European-Non Finnish (NFE) AF: 9.01e-7 AC: 1 AN: 1109578

Other (OTH) AF: 0.00 AC: 0 AN: 60328

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.00000000770867), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Pheochromocytoma/paraganglioma syndrome 2 Uncertain:1

Dec 04, 2023

Baylor Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not provided Uncertain:1

Jul 19, 2023

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

May 31, 2025

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.Y120C variant (also known as c.359A>G), located in coding exon 3 of the SDHAF2 gene, results from an A to G substitution at nucleotide position 359. The tyrosine at codon 120 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. -

Hereditary pheochromocytoma-paraganglioma Uncertain:1

Oct 20, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces tyrosine, which is neutral and polar, with cysteine, which is neutral and slightly polar, at codon 120 of the SDHAF2 protein (p.Tyr120Cys). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with SDHAF2-related conditions. ClinVar contains an entry for this variant (Variation ID: 234164). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be disruptive. 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	Uncertain	0.55
BayesDel_addAF	Pathogenic	0.43	D
BayesDel_noAF	Pathogenic	0.39
CADD	Pathogenic	29
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.85	.;D;.;.
Eigen	Pathogenic	0.89
Eigen_PC	Pathogenic	0.86
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.99	D;D;D;D
M_CAP	Benign	0.069	D
MetaRNN	Pathogenic	0.90	D;D;D;D
MetaSVM	Uncertain	0.45	D
MutationAssessor	Pathogenic	3.4	.;M;.;.
PhyloP100		8.5
PrimateAI	Uncertain	0.71	T
PROVEAN	Pathogenic	-8.7	D;D;.;.
REVEL	Pathogenic	0.81
Sift	Pathogenic	0.0	D;D;.;.
Sift4G	Pathogenic	0.0010	D;D;D;D
Polyphen		0.99	.;D;.;.
Vest4		0.93, 0.89, 0.92
MutPred		0.57		Gain of catalytic residue at W121 (P = 0.0032);Gain of catalytic residue at W121 (P = 0.0032);Gain of catalytic residue at W121 (P = 0.0032);Gain of catalytic residue at W121 (P = 0.0032);
MVP		0.78
MPC		0.76
ClinPred		1.0	D
GERP RS		5.9
Varity_R		0.97
gMVP		0.71
Mutation Taster		=16/84	disease causing

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: rs772928706; hg19: chr11-61205574;