1-241500502-G-C

Position:

• chr1-241500502-G-C

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 4P and 2B. PM1 PM2 BP4_Moderate

The NM_000143.4(FH):​c.1325C>G​(p.Thr442Arg) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts 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. T442I) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 31)
• Consequence: FH NM_000143.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 2.39

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 (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 2 benign, 11 uncertain in NM_000143.4
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.24459773).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
FH	NM_000143.4	c.1325C>G	p.Thr442Arg	missense_variant	9/10	ENST00000366560.4	NP_000134.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
FH	ENST00000366560.4	c.1325C>G	p.Thr442Arg	missense_variant	9/10	1	NM_000143.4	ENSP00000355518.4

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 31

Bravo AF: 0.00000756

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 26, 2021

This sequence change replaces threonine with arginine at codon 442 of the FH protein (p.Thr442Arg). The threonine residue is moderately conserved and there is a moderate physicochemical difference between threonine and arginine. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals affected with FH-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated. 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

Sep 16, 2021

The p.T442R variant (also known as c.1325C>G), located in coding exon 9 of the FH gene, results from a C to G substitution at nucleotide position 1325. The threonine at codon 442 is replaced by arginine, an amino acid with similar properties. This amino acid position is well conserved in available vertebrate species. In addition, the in silico prediction for this alteration is inconclusive. 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	0.079
BayesDel_addAF	Uncertain	0.12	D
BayesDel_noAF	Uncertain	-0.070
CADD	Benign	18
DANN	Benign	0.95
DEOGEN2	Benign	0.22	T
Eigen	Benign	-0.52
Eigen_PC	Benign	-0.23
FATHMM_MKL	Uncertain	0.88	D
LIST_S2	Uncertain	0.94	D
M_CAP	Uncertain	0.11	D
MetaRNN	Benign	0.24	T
MetaSVM	Uncertain	0.69	D
MutationAssessor	Benign	-0.83	N
PrimateAI	Uncertain	0.64	T
PROVEAN	Benign	1.0	N
REVEL	Uncertain	0.40
Sift	Benign	0.48	T
Sift4G	Benign	0.92	T
Polyphen		0.0	B
Vest4		0.49
MutPred		0.30		Gain of loop (P = 0.1069);
MVP		0.91
MPC		0.32
ClinPred		0.43	T
GERP RS		3.8
Varity_R		0.13
gMVP		0.92

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: rs1060500899; hg19: chr1-241663802; COSMIC: COSV63818212;