rs768341401

chr1-241512105-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_000143.4(FH):c.417G>A(p.Val139=) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,612 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: FH NM_000143.4 synonymous
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:5
• Conservation: PhyloP100: 2.05

Genes affected

FH (HGNC:3700): (fumarate hydratase) The protein encoded by this gene is an enzymatic component of the tricarboxylic acid (TCA) cycle, or Krebs cycle, and catalyzes the formation of L-malate from fumarate. It exists in both a cytosolic form and an N-terminal extended form, differing only in the translation start site used. The N-terminal extended form is targeted to the mitochondrion, where the removal of the extension generates the same form as in the cytoplasm. It is similar to some thermostable class II fumarases and functions as a homotetramer. Mutations in this gene can cause fumarase deficiency and lead to progressive encephalopathy. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
FH	NM_000143.4	c.417G>A	p.Val139=	synonymous_variant	4/10	ENST00000366560.4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
FH	ENST00000366560.4	c.417G>A	p.Val139=	synonymous_variant	4/10	1	NM_000143.4	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000797 AC: 2 AN: 250992 Hom.: 0 AF XY: 0.0000147 AC XY: 2 AN XY: 135636

Gnomad AFR exome AF: 0.00

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: 0.00

Gnomad NFE exome AF: 0.0000176

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461612 Hom.: 0 Cov.: 31 AF XY: 0.00000275 AC XY: 2 AN XY: 727118

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: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

EpiCase AF: 0.00

EpiControl AF: 0.000119

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:3

Uncertain significance, criteria provided, single submitter	clinical testing	Invitae	Feb 01, 2024	This sequence change affects codon 139 of the FH mRNA. It is a 'silent' change, meaning that it does not change the encoded amino acid sequence of the FH protein. This variant is present in population databases (rs768341401, gnomAD 0.002%). This variant has not been reported in the literature in individuals affected with FH-related conditions. ClinVar contains an entry for this variant (Variation ID: 573543). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site. 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. -
Uncertain significance, criteria provided, single submitter	clinical testing	Quest Diagnostics Nichols Institute San Juan Capistrano	Jul 19, 2023	This variant has not been reported as a germline variant in individuals with FH-related conditions in the published literature. The frequency of this variant in the general population, 0.000008 (2/250992 chromosomes (Genome Aggregation Database, http://gnomad.broadinstitute.org)), is uninformative in the assessment of its pathogenicity. Analysis of this variant using software algorithms for the prediction of the effect of nucleotide changes on FH mRNA splicing yielded predictions that this variant may result in the gain of a cryptic splice site without affecting the natural splice sites . Based on the available information, we are unable to determine the clinical significance of this variant. -
Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	Aug 16, 2022	Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports a deleterious effect on splicing; Has not been previously published as pathogenic or benign to our knowledge -

Fumarase deficiency Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Baylor Genetics

May 15, 2023

- -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

May 05, 2023

The c.417G>A variant (also known as p.V139V), located in coding exon 4 of the FH gene, results from a G to A substitution at nucleotide position 417. This nucleotide substitution does not change the valine at codon 139. This nucleotide position is well conserved in available vertebrate species. In silico splice site analysis predicts that this alteration will result in the creation or strengthening of a novel splice acceptor site; however, direct evidence is insufficient at this time (Ambry internal data). 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
BayesDel_noAF	Benign	-0.28
Cadd	Benign	23
Dann	Benign	0.82
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.87		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.87		Position offset: -2

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

Publications

LitVar

Other links and lift over

dbSNP: rs768341401; hg19: chr1-241675405;