NM_021870.3:c.1022G>A

Variant names:

• chr4-154606812-C-T
• rs1553965519
• NM_021870.3:c.1022G>A

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_021870.3(FGG):​c.1022G>A​(p.Trp341*) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000205 in 1,461,720 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: FGG NM_021870.3 stop_gained
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 0.631
• Publications: 0 publications found

Genes affected

FGG (HGNC:3694): (fibrinogen gamma chain) The protein encoded by this gene is the gamma component of fibrinogen, a blood-borne glycoprotein comprised of three pairs of nonidentical polypeptide chains. Following vascular injury, fibrinogen is cleaved by thrombin to form fibrin which is the most abundant component of blood clots. In addition, various cleavage products of fibrinogen and fibrin regulate cell adhesion and spreading, display vasoconstrictor and chemotactic activities, and are mitogens for several cell types. Mutations in this gene lead to several disorders, including dysfibrinogenemia, hypofibrinogenemia and thrombophilia. Alternative splicing results in transcript variants encoding different isoforms. [provided by RefSeq, Aug 2015]

FGG Gene-Disease associations (from GenCC):

• congenital fibrinogen deficiency

  Inheritance: SD Classification: DEFINITIVE Submitted by: ClinGen
• familial dysfibrinogenemia

  Inheritance: AD Classification: STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Orphanet
• thrombophilia

  Inheritance: AD, AR Classification: STRONG Submitted by: Genomics England PanelApp
• congenital afibrinogenemia

  Inheritance: AR Classification: STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Orphanet
• familial hypofibrinogenemia

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 12 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 4-154606812-C-T is Pathogenic according to our data. Variant chr4-154606812-C-T is described in ClinVar as Pathogenic. ClinVar VariationId is 504885.Status of the report is criteria_provided_single_submitter, 1 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_021870.3. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	FGG	NM_021870.3	MANE Select	c.1022G>A	p.Trp341*	stop_gained	Exon 8 of 9	NP_068656.2
	FGG	NM_000509.6		c.1022G>A	p.Trp341*	stop_gained	Exon 8 of 10	NP_000500.2

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	FGG	ENST00000336098.8	TSL:2 MANE Select	c.1022G>A	p.Trp341*	stop_gained	Exon 8 of 9	ENSP00000336829.3
	FGG	ENST00000404648.7	TSL:1	c.1022G>A	p.Trp341*	stop_gained	Exon 8 of 10	ENSP00000384860.3
	FGG	ENST00000407946.5	TSL:5	c.1046G>A	p.Trp349*	stop_gained	Exon 8 of 9	ENSP00000384552.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461720 Hom.: 0 Cov.: 31 AF XY: 0.00000413 AC XY: 3 AN XY: 727164

African (AFR) AF: 0.00 AC: 0 AN: 33462

American (AMR) AF: 0.00 AC: 0 AN: 44708

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

East Asian (EAS) AF: 0.00 AC: 0 AN: 39698

South Asian (SAS) AF: 0.00 AC: 0 AN: 86250

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53420

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00000180 AC: 2 AN: 1111892

Other (OTH) AF: 0.0000166 AC: 1 AN: 60390

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Congenital afibrinogenemia Pathogenic:1

Apr 27, 2016

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.Trp341X variant in FGG has not been previously reported in individuals wit h afibrinogenemia/hypofibrinogenemia and is absent from large population studies . This nonsense variant leads to a premature termination codon at position 341 w hich is predicted to lead to a truncated or absent protein. Loss of function var iants in FGG have been shown to cause afibrinogenemia in the homozygous state an d hypofibrinogenemia (though not always symptomatic) in the heterozygous state. In summary, this variant meets our criteria to be classified as pathogenic for a fibrinogenemia in an autosomal recessive manner.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.51	D
BayesDel_noAF	Pathogenic	0.50
CADD	Pathogenic	38
DANN	Uncertain	0.99
Eigen	Pathogenic	0.91
Eigen_PC	Pathogenic	0.79
FATHMM_MKL	Benign	0.60	D
PhyloP100		0.63
Vest4		0.89
GERP RS		5.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		2.7
Mutation Taster		=2/198	disease causing (ClinVar)

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: rs1553965519; hg19: chr4-155527964;