1-241497927-A-T

Variant names:

• chr1-241497927-A-T
• rs786202199
• NM_000143.4:c.1434T>A

Variant summary

Our verdict is Uncertain significance. The variant received 1 ACMG points: 3P and 2B. PM1 PP2 BP4_Moderate

The NM_000143.4(FH):​c.1434T>A​(p.Asn478Lys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000479 in 1,461,682 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 17/22 in silico tools predict a benign 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. N478S) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 0.0000048 (0 hom.)
• Consequence: FH NM_000143.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: -1.03
• Publications: 2 publications found

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]

FH Gene-Disease associations (from GenCC):

• hereditary leiomyomatosis and renal cell cancer

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: ClinGen, Ambry Genetics, G2P, Genomics England PanelApp, Labcorp Genetics (formerly Invitae), Orphanet
• fumaric aciduria

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Orphanet, Labcorp Genetics (formerly Invitae), Ambry Genetics
• pheochromocytoma-paraganglioma

  Inheritance: AD Classification: STRONG Submitted by: Ambry Genetics
• leiomyosarcoma

  Inheritance: AD Classification: MODERATE Submitted by: Genomics England PanelApp
• hereditary pheochromocytoma-paraganglioma

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 1 ACMG points.

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 18 uncertain in NM_000143.4
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 132 curated pathogenic missense variants (we use a threshold of 10). The gene has 17 curated benign missense variants. Gene score misZ: 1.2708 (below the threshold of 3.09). Trascript score misZ: 2.0634 (below the threshold of 3.09). GenCC associations: The gene is linked to fumaric aciduria, hereditary leiomyomatosis and renal cell cancer, hereditary pheochromocytoma-paraganglioma, leiomyosarcoma, pheochromocytoma-paraganglioma.
• BP4: Computational evidence support a benign effect (MetaRNN=0.099615335).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
FH	NM_000143.4	c.1434T>A	p.Asn478Lys	missense_variant	Exon 10 of 10	ENST00000366560.4	NP_000134.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
FH	ENST00000366560.4	c.1434T>A	p.Asn478Lys	missense_variant	Exon 10 of 10	1	NM_000143.4	ENSP00000355518.4

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 0.00000479 AC: 7 AN: 1461682 Hom.: 0 Cov.: 31 AF XY: 0.00000550 AC XY: 4 AN XY: 727146

African (AFR) AF: 0.00 AC: 0 AN: 33470

American (AMR) AF: 0.00 AC: 0 AN: 44698

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

East Asian (EAS) AF: 0.000151 AC: 6 AN: 39672

South Asian (SAS) AF: 0.00 AC: 0 AN: 86248

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53416

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5716

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111950

Other (OTH) AF: 0.0000166 AC: 1 AN: 60380

GnomAD4 genome Cov.: 31

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:1

Aug 31, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces asparagine, which is neutral and polar, with lysine, which is basic and polar, at codon 478 of the FH protein (p.Asn478Lys). This variant is not present in population databases (gnomAD no frequency). 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: 647389). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is not expected to disrupt FH protein function with a negative predictive value of 95%. 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. -

Fumarase deficiency Uncertain:1

Aug 08, 2020

Natera, Inc.

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Hereditary cancer-predisposing syndrome Uncertain:1

Sep 19, 2023

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.N478K variant (also known as c.1434T>A), located in coding exon 10 of the FH gene, results from a T to A substitution at nucleotide position 1434. The asparagine at codon 478 is replaced by lysine, an amino acid with similar properties. This amino acid position is not well conserved in available vertebrate species. In addition, this alteration is predicted to be tolerated 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	Benign	0.12
BayesDel_addAF	Benign	-0.15	T
BayesDel_noAF	Benign	-0.45
CADD	Benign	11
DANN	Benign	0.91
DEOGEN2	Benign	0.36	T
Eigen	Benign	-0.81
Eigen_PC	Benign	-0.71
FATHMM_MKL	Benign	0.23	N
LIST_S2	Uncertain	0.88	D
M_CAP	Benign	0.019	T
MetaRNN	Benign	0.10	T
MetaSVM	Benign	-0.81	T
MutationAssessor	Benign	0.86	L
PhyloP100		-1.0
PrimateAI	Benign	0.43	T
PROVEAN	Benign	-0.67	N
REVEL	Benign	0.20
Sift	Benign	0.58	T
Sift4G	Benign	0.45	T
Polyphen		0.0010	B
Vest4		0.12
MutPred		0.42		Gain of MoRF binding (P = 0.0412);
MVP		0.73
MPC		0.33
ClinPred		0.23	T
GERP RS		-0.55
Varity_R		0.16
gMVP		0.76
Mutation Taster		=56/44	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: rs786202199; hg19: chr1-241661227;