rs121918093

Variant names:

• chr18-31592944-G-A
• rs121918093
• NM_000371.4:c.118G>A

Your query was ambiguous. Multiple possible variants found:

• chr18-31592944-G-A
• chr18-31592944-G-C

Variant summary

Our verdict is Pathogenic. The variant received 21 ACMG points: 21P and 0B. PS3 PM1 PM2 PM5 PP2 PP3_Moderate PP5_Very_Strong

The NM_000371.4(TTR):​c.118G>A​(p.Val40Ile) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000124 in 1,614,026 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 (★★). ClinVar reports functional evidence for this variant: "SCV001207082: Experimental studies have shown that this missense change affects TTR function (PMID:8692810, 15820680, 17503405)." and additional evidence is available in ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. V40A) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: TTR NM_000371.4 missense
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:8
• Conservation: PhyloP100: 7.59
• Publications: 27 publications found

Genes affected

TTR (HGNC:12405): (transthyretin) This gene encodes one of the three prealbumins, which include alpha-1-antitrypsin, transthyretin and orosomucoid. The encoded protein, transthyretin, is a homo-tetrameric carrier protein, which transports thyroid hormones in the plasma and cerebrospinal fluid. It is also involved in the transport of retinol (vitamin A) in the plasma by associating with retinol-binding protein. The protein may also be involved in other intracellular processes including proteolysis, nerve regeneration, autophagy and glucose homeostasis. Mutations in this gene are associated with amyloid deposition, predominantly affecting peripheral nerves or the heart, while a small percentage of the gene mutations are non-amyloidogenic. The mutations are implicated in the etiology of several diseases, including amyloidotic polyneuropathy, euthyroid hyperthyroxinaemia, amyloidotic vitreous opacities, cardiomyopathy, oculoleptomeningeal amyloidosis, meningocerebrovascular amyloidosis and carpal tunnel syndrome. [provided by RefSeq, Aug 2017]

TTR Gene-Disease associations (from GenCC):

• amyloidosis, hereditary systemic 1

  Inheritance: AD Classification: DEFINITIVE Submitted by: G2P
• familial amyloid neuropathy

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, Ambry Genetics, Labcorp Genetics (formerly Invitae)
• hereditary ATTR amyloidosis

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• heart conduction disease

  Inheritance: AD Classification: STRONG Submitted by: Genomics England PanelApp
• ATTRV122I amyloidosis

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 21 ACMG points.

• PS3: PS3 evidence extracted from ClinVar submissions: SCV001207082: Experimental studies have shown that this missense change affects TTR function (PMID: 8692810, 15820680, 17503405).; SCV006059843: Functional studies conducted using patient tissue and purified protein demonstrated that this variant impacts protein stability (PMID: 8692810; 15820680).; SCV000209366: The Val40Ile variant (also known as Val20Ile, due to a difference in cDNA numbering) in the TTR gene, has been published in association with cardiac amyloidosis (Jenne D et al., 1996; Barreiros A et al., 2010). Jenne et al. (1996) reported the Val40Ile mutation in a German family with severe amyloid cardiomyopathy. The same study demonstrated that Val40Ile causes significant loss of tetramer stability.; SCV002048940: Functional analyses of the variant protein show significantly reduced tetramer stability (Jenne 1996, Atland 2007, Sekijima 2005).; SCV002640431: A functional study found that, although the monomer of the protein with this alteration was more stable than the wild type, the dimer-dimer interaction appeared to be weakened, possibly leading to instability of the protein and a potential mechanism for reduced TTR concentration in plasma that was observed in carriers of the alteration (Altland, 2007).
• PM1: In a hotspot region, there are 14 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 8 uncertain in NM_000371.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr18-31592945-T-C is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 2169600.Status of the report is criteria_provided_single_submitter, 1 stars.
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 108 curated pathogenic missense variants (we use a threshold of 10). The gene has 3 curated benign missense variants. Gene score misZ: 1.0149 (below the threshold of 3.09). Trascript score misZ: 1.5458 (below the threshold of 3.09). GenCC associations: The gene is linked to hereditary ATTR amyloidosis, heart conduction disease, familial amyloid neuropathy, ATTRV122I amyloidosis, amyloidosis, hereditary systemic 1.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.871
• PP5: Variant 18-31592944-G-A is Pathogenic according to our data. Variant chr18-31592944-G-A is described in ClinVar as Pathogenic. ClinVar VariationId is 13455.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000371.4. 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
	TTR	NM_000371.4	MANE Select	c.118G>A	p.Val40Ile	missense	Exon 2 of 4	NP_000362.1	P02766

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTR	ENST00000237014.8	TSL:1 MANE Select	c.118G>A	p.Val40Ile	missense	Exon 2 of 4	ENSP00000237014.4	P02766
	TTR	ENST00000649620.1		c.118G>A	p.Val40Ile	missense	Exon 4 of 6	ENSP00000497927.1	P02766
	TTR	ENST00000858988.1		c.118G>A	p.Val40Ile	missense	Exon 4 of 6	ENSP00000529047.1

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152206 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461820 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 727218

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33476

American (AMR) AF: 0.00 AC: 0 AN: 44720

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53408

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

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111966

Other (OTH) AF: 0.00 AC: 0 AN: 60390

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152206 Hom.: 0 Cov.: 32 AF XY: 0.0000134 AC XY: 1 AN XY: 74350

African (AFR) AF: 0.00 AC: 0 AN: 41446

American (AMR) AF: 0.00 AC: 0 AN: 15288

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3472

East Asian (EAS) AF: 0.00 AC: 0 AN: 5198

South Asian (SAS) AF: 0.00 AC: 0 AN: 4834

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10614

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.0000147 AC: 1 AN: 68034

Other (OTH) AF: 0.00 AC: 0 AN: 2094

Alfa AF: 0.00000469 Hom.: 0

Bravo AF: 0.00000378

ClinVar

ClinVar submissions

Significance: Pathogenic

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
4	-	-	Amyloidosis, hereditary systemic 1 (4)
3	-	-	not provided (3)
1	-	-	Cardiovascular phenotype (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.13
BayesDel_addAF	Pathogenic	0.40	D
BayesDel_noAF	Pathogenic	0.33
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.76	D
Eigen	Pathogenic	0.73
Eigen_PC	Uncertain	0.60
FATHMM_MKL	Uncertain	0.93	D
LIST_S2	Uncertain	0.96	D
M_CAP	Pathogenic	0.47	D
MetaRNN	Pathogenic	0.87	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.6	H
PhyloP100		7.6
PrimateAI	Benign	0.42	T
PROVEAN	Benign	-0.82	N
REVEL	Pathogenic	0.70
Sift	Uncertain	0.0030	D
Sift4G	Uncertain	0.038	D
Polyphen		1.0	D
Vest4		0.55
MutPred		0.64		Gain of methylation at K35 (P = 0.0905)
MVP		0.99
MPC		1.2
ClinPred		0.99	D
GERP RS		5.7
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.79
gMVP		0.92
Mutation Taster		=18/82	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: rs121918093; hg19: chr18-29172907;