rs137852413

chrX-154961131-A-CchrX-154961131-A-G

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PM1 PM2 PM5 PP3_Strong PP5_Moderate

The NM_000132.4(F8):c.1481T>G(p.Ile494Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. I494T) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 22)
• Consequence: F8 NM_000132.4 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 7.58

Genes affected

F8 (HGNC:3546): (coagulation factor VIII) This gene encodes coagulation factor VIII, which participates in the intrinsic pathway of blood coagulation; factor VIII is a cofactor for factor IXa which, in the presence of Ca+2 and phospholipids, converts factor X to the activated form Xa. This gene produces two alternatively spliced transcripts. Transcript variant 1 encodes a large glycoprotein, isoform a, which circulates in plasma and associates with von Willebrand factor in a noncovalent complex. This protein undergoes multiple cleavage events. Transcript variant 2 encodes a putative small protein, isoform b, which consists primarily of the phospholipid binding domain of factor VIIIc. This binding domain is essential for coagulant activity. Defects in this gene results in hemophilia A, a common recessive X-linked coagulation disorder. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Pathogenic. Variant got 12 ACMG points.

• PM1: In a hotspot region, there are 5 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 2 uncertain in NM_000132.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chrX-154961131-A-G is described in ClinVar as [Pathogenic]. Clinvar id is 10216.Status of the report is no_assertion_criteria_provided, 0 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.992
• PP5: Variant X-154961131-A-C is Pathogenic according to our data. Variant chrX-154961131-A-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1330924.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
F8	NM_000132.4	c.1481T>G	p.Ile494Ser	missense_variant	10/26	ENST00000360256.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
F8	ENST00000360256.9	c.1481T>G	p.Ile494Ser	missense_variant	10/26	1	NM_000132.4	P1
F8	ENST00000647125.1	c.*1357T>G		3_prime_UTR_variant, NMD_transcript_variant	11/14

Frequencies

GnomAD3 genomes Cov.: 22

GnomAD4 exome Cov.: 27

GnomAD4 genome Cov.: 22

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Hereditary factor VIII deficiency disease Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Jul 23, 2021

The F8 c.1481T>G; p.Ile494Ser variant is reported in the literature in at least one individual affected with moderate to severe hemophilia A (see F8 database and references therein). This variant is absent from the Genome Aggregation Database, indicating it is not a common polymorphism. Additionally, another variant at this codon (c.1481T>C, p.Ile494Thr) has been reported in individuals with mild hemophilia A and is considered pathogenic (Schwaab 1995). The isoleucine at codon 494 is highly conserved, and computational analyses predict that this variant is deleterious (REVEL: 0.983). Based on available information, this variant is considered to be likely pathogenic. References: Link to Factor VIII database: https://f8-db.eahad.org/index.php Johnsen JM et al. Novel approach to genetic analysis and results in 3000 hemophilia patients enrolled in the My Life, Our Future initiative. Blood Adv. 2017 May 18;1(13):824-834. PMID: 29296726. Schwaab R et al. Characterization of mutations within the factor VIII gene of 73 unrelated mild and moderate haemophiliacs. Br J Haematol. 1995 Oct;91(2):458-64. PMID: 8547094. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.94
BayesDel_addAF	Pathogenic	0.72	D
BayesDel_noAF	Pathogenic	0.80
Cadd	Pathogenic	26
Dann	Uncertain	1.0
DEOGEN2	Pathogenic	1.0	D
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.86	D
M_CAP	Pathogenic	0.93	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	0.98	D
MutationAssessor	Pathogenic	4.0	H
MutationTaster	Benign	0.99	D
PrimateAI	Uncertain	0.61	T
PROVEAN	Pathogenic	-4.9	D
REVEL	Pathogenic	0.98
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0010	D
Polyphen		1.0	D
Vest4		0.88
MutPred		0.90		Gain of disorder (P = 0.0019);
MVP		1.0
MPC		2.0
ClinPred		1.0	D
GERP RS		4.9
Varity_R		0.99
gMVP		1.0

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

No publications associated with this variant yet.

Other links and lift over

hg19: chrX-154189406;