NM_000132.4:c.1988_1989delCAinsTC

Variant names:

• chrX-154947822-TG-GA
• NM_000132.4:c.1988_1989delCAinsTC
• F8 p.Ala663Val

Variant summary

Our verdict is Uncertain significance. The variant received 5 ACMG points: 5P and 0B. PS1 PP2

The NM_000132.4(F8):​c.1988_1989delCAinsTC​(p.Ala663Val) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. It is difficult to determine the true allele frequency of this variant because it is of type MNV, and the frequency of such variant types in population databases may be underestimated and unreliable. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another nucleotide change resulting in the same amino acid substitution has been previously reported as Pathogenic in ClinVar. The gene F8 is included in the ClinGen Criteria Specification Registry.

• Frequency: Genomes: not found (cov: 22)
• Consequence: F8 NM_000132.4 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 5.09
• Publications: 0 publications found

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]

F8 Gene-Disease associations (from GenCC):

• hemophilia A

  Inheritance: XL Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), ClinGen
• mild hemophilia A

  Inheritance: XL Classification: SUPPORTIVE Submitted by: Orphanet
• moderately severe hemophilia A

  Inheritance: XL Classification: SUPPORTIVE Submitted by: Orphanet
• severe hemophilia A

  Inheritance: XL Classification: SUPPORTIVE Submitted by: Orphanet
• symptomatic form of hemophilia A in female carriers

  Inheritance: XL Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Specifications for F8 are available in the ClinGen Criteria Specification Registry and recommended for reference when assigning criteria.

Our verdict: Uncertain_significance. The variant received 5 ACMG points.

• PS1: Transcript NM_000132.4 (F8) is affected with MISSENSE_VARIANT having same AA change as one Pathogenic present in ClinVar.
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 327 curated pathogenic missense variants (we use a threshold of 10). The gene has 28 curated benign missense variants. Gene score misZ: 2.4669 (below the threshold of 3.09). Trascript score misZ: NaN (below the threshold of 3.09). GenCC associations: The gene is linked to mild hemophilia A, hemophilia A, symptomatic form of hemophilia A in female carriers, severe hemophilia A, moderately severe hemophilia A.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000132.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	F8	NM_000132.4	MANE Select	c.1988_1989delCAinsTC	p.Ala663Val	missense	N/A	NP_000123.1	P00451-1

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	F8	ENST00000360256.9	TSL:1 MANE Select	c.1988_1989delCAinsTC	p.Ala663Val	missense	N/A	ENSP00000353393.4	P00451-1
	F8	ENST00000647125.1		n.*1779+6069_*1779+6070delCAinsTC		intron	N/A	ENSP00000496062.1	A0A2R8Y7J7

Frequencies

GnomAD3 genomes Cov.: 22

We have no GnomAD4 exomes data on this position. Probably position not covered by the project.

GnomAD4 genome Cov.: 22

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		5.1

Splicing

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

MaxEntScan Visualizer can be used to analyze the impact of this mutation on the neighboring sequence.

Other links and lift over

hg19: chrX-154176097;