rs749527870

Positions:

• chr11-61437849-G-A

Variant summary

Our verdict is Pathogenic. Variant got 22 ACMG points: 22P and 0B. PVS1 PM2 PP3_Strong PP5_Very_Strong

The NM_017841.4(SDHAF2):​c.260+1G>A variant causes a splice donor change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000685 in 1,460,222 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: SDHAF2 NM_017841.4 splice_donor
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 8.97

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]

(HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 22 ACMG points.

• PVS1: Splicing variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 11-61437849-G-A is Pathogenic according to our data. Variant chr11-61437849-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 463821.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SDHAF2	NM_017841.4	c.260+1G>A		splice_donor_variant		ENST00000301761.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SDHAF2	ENST00000301761.7	c.260+1G>A		splice_donor_variant		1	NM_017841.4	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.85e-7 AC: 1 AN: 1460222 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 726434

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000224

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hereditary pheochromocytoma-paraganglioma Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	All of Us Research Program, National Institutes of Health	Dec 07, 2023	The c.260+1G>A variant of the SDHAF2 gene is predicted to disrupt mRNA splicing (spliceAI 0.96), affecting the donor splice site in intron 2 and resulting in an absent or aberrant protein product. Loss-of-function variants in SDHAF2 gene are known to be pathogenic (PMID: 22241717, 31687641, 26096992). This variant has not been reported in the literature in individuals affected with SDHAF2-related conditions. This variant has a very low frequency (1/248010) in the general population according to gnomAD. For these reasons, the c.260+1G>A variant in the SDHAF2 gene has been classified as likely pathogenic. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Invitae	Dec 22, 2023	This sequence change affects a donor splice site in intron 2 of the SDHAF2 gene. RNA analysis indicates that disruption of this splice site induces altered splicing and may result in an absent or disrupted protein product. The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. 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: 463821). Studies have shown that disruption of this splice site results in skipping of exon 2 and exons 2-3 and introduces a premature termination codon (Invitae). The resulting mRNA is expected to undergo nonsense-mediated decay. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

Hereditary cancer-predisposing syndrome Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

May 19, 2023

The c.260+1G>A intronic variant results from a G to A substitution one nucleotide after coding exon 2 of the SDHAF2 gene. RNA studies have demonstrated that this alteration results in abnormal splicing in the set of samples tested (Ambry internal data). In silico splice site analysis predicts that this alteration will weaken the native splice donor site. Based on the majority of available evidence to date, this variant is likely to be pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.44
CADD	Pathogenic	33
DANN	Uncertain	1.0
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.1
FATHMM_MKL	Pathogenic	0.99	D
MutationTaster	Benign	1.0	D;D
GERP RS		5.9

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.94
SpliceAI score (max)		0.96		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.96		Position offset: -1

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs749527870; hg19: chr11-61205321;