chrX-154929410-AT-A

Variant names:

• chrX-154929410-AT-A
• rs387906455
• NM_000132.4:c.4379delA

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000132.4(F8):​c.4379delA​(p.Asn1460IlefsTer5) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000182 in 1,096,301 control chromosomes in the GnomAD database, with no homozygous occurrence. There are 1 hemizygotes in GnomAD. Variant has been reported in ClinVar as Likely pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 22)
  • Exomes 𝑓: 0.0000018 (0 hom. 1 hem.)
• Consequence: F8 NM_000132.4 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:7
• Conservation: PhyloP100: 0.866

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 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant X-154929410-AT-A is Pathogenic according to our data. Variant chrX-154929410-AT-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 10261.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chrX-154929410-AT-A is described in Lovd as [Likely_pathogenic]. Variant chrX-154929410-AT-A is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
F8	NM_000132.4	c.4379delA	p.Asn1460IlefsTer5	frameshift_variant	Exon 14 of 26	ENST00000360256.9	NP_000123.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
F8	ENST00000360256.9	c.4379delA	p.Asn1460IlefsTer5	frameshift_variant	Exon 14 of 26	1	NM_000132.4	ENSP00000353393.4

Frequencies

GnomAD3 genomes Cov.: 22

GnomAD4 exome AF: 0.00000182 AC: 2 AN: 1096301 Hom.: 0 Cov.: 32 AF XY: 0.00000276 AC XY: 1 AN XY: 362065

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: 0.00000238

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 22

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:7

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hereditary factor VIII deficiency disease Pathogenic:7

Pathogenic, no assertion criteria provided	clinical testing	Pele Pequeno Principe Research Institute, Faculdades Pequeno Principe	-	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Genomic Medicine Center of Excellence, King Faisal Specialist Hospital and Research Centre	Apr 04, 2024	- -
Pathogenic, criteria provided, single submitter	clinical testing	Mendelics	May 28, 2019	- -
Pathogenic, criteria provided, single submitter	clinical testing	ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories	Oct 02, 2021	The F8 c.4379delA; p.Asn1460IlefsTer5 variant (rs387906455) also reported as c.4550delA; p.Asn1441IlefsTer5, is reported in multiple patients with severe hemophilia A (Naylor 1993, Tuddenham 1991, Wang 2010, Factor VIII variant database). This variant is also reported in ClinVar (Variation ID: 10261). It is only observed on two alleles in the Genome Aggregation Database, indicating it is not a common polymorphism. This variant causes a frameshift by deleting a single nucleotide, so it is predicted to result in a truncated protein or mRNA subject to nonsense-mediated decay. Based on available information, this variant is considered to be pathogenic. References: Factor VIII variant database: http://www.factorviii-db.org/ Naylor J et al. Characteristic mRNA abnormality found in half the patients with severe haemophilia A is due to large DNA inversions. Hum Mol Genet. 1993; 2(11):1773-8. Tuddenham EG et al. Haemophilia A: database of nucleotide substitutions, deletions, insertions and rearrangements of the factor VIII gene. Nucleic Acids Res. 1991; 19(18):4821-33. Wang X et al. The prevalence of factor VIII inhibitors and genetic aspects of inhibitor development in Chinese patients with haemophilia A. Haemophilia. 2010; 16(4):632-9. -
Pathogenic, criteria provided, single submitter	clinical testing	3billion, Medical Genetics	Feb 23, 2023	The variant is observed at an extremely low frequency in the gnomAD v2.1.1 dataset (total allele frequency: <0.001%). This variant was predicted to result in a loss or disruption of normal protein function through nonsense-mediated decay (NMD) or protein truncation. Multiple pathogenic variants are reported downstream of the variant. The variant has been reported at least twice as pathogenic with clinical assertions and evidence for the classification (ClinVar ID: VCV000010261 / PMID: 1923751). Therefore, this variant is classified as Pathogenic according to the recommendation of ACMG/AMP guideline. -
Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Dec 24, 2024	Variant summary: F8 c.4379delA (p.Asn1460IlefsX5) results in a premature termination codon, predicted to cause absence of the protein due to nonsense mediated decay, which is a commonly known mechanism for disease. The frequency data for this variant in gnomAD is considered unreliable, as metrics indicate poor data quality at this position. c.4379delA has been reported in the literature in individuals affected with Hemophilia (example, Miller_2011). These data indicate that the variant may be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publication has been ascertained in the context of this evaluation (PMID: 22103590). ClinVar contains an entry for this variant (Variation ID: 10261). Based on the evidence outlined above, the variant was classified as pathogenic. -
Pathogenic, no assertion criteria provided	literature only	OMIM	Nov 01, 1993	- -

Computational scores

Source: dbNSFP v4.3

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: rs387906455; hg19: chrX-154157685;