18-31595125-C-G

Position:

• chr18-31595125-C-G

Variant summary

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

The NM_000371.4(TTR):​c.206C>G​(p.Thr69Ser) variant causes a missense change. 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. T69A) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: TTR NM_000371.4 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 4.33

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]

ACMG classification

Verdict is Pathogenic. Variant got 12 ACMG points.

• PM1: In a hotspot region, there are 12 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 7 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 chr18-31595125-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 1454801.Status of the report is criteria_provided_single_submitter, 1 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.973
• PP5: Variant 18-31595125-C-G is Pathogenic according to our data. Variant chr18-31595125-C-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 538164.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TTR	NM_000371.4	c.206C>G	p.Thr69Ser	missense_variant	3/4	ENST00000237014.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TTR	ENST00000237014.8	c.206C>G	p.Thr69Ser	missense_variant	3/4	1	NM_000371.4	P1
TTR	ENST00000649620.1	c.206C>G	p.Thr69Ser	missense_variant	5/6			P1
TTR	ENST00000610404.5	c.110C>G	p.Thr37Ser	missense_variant	3/4	5
TTR	ENST00000541025.2	n.232C>G		non_coding_transcript_exon_variant	3/3	2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Amyloidosis, hereditary systemic 1 Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Oct 10, 2017

Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C55"). This variant has been reported in several individuals affected with hereditary amyloidosis (PMID: 25044787, 26115788, Invitae). This variant is also known as p.Thr49Ser in the literature. This variant is not present in population databases (ExAC no frequency). This sequence change replaces threonine with serine at codon 69 of the TTR protein (p.Thr69Ser). The threonine residue is highly conserved and there is a small physicochemical difference between threonine and serine. A different missense substitution at this codon (p.Thr69Ala) has been determined to be pathogenic (PMID: 1301926, 17503405, 20209591, 23713495, 21692911, 27859927). This suggests that the threonine residue is critical for TTR protein function and that other missense substitutions at this position may also be pathogenic. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.65
BayesDel_addAF	Pathogenic	0.26	D
BayesDel_noAF	Uncertain	0.13
CADD	Pathogenic	26
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.98	D;D;T;.
Eigen	Pathogenic	0.93
Eigen_PC	Pathogenic	0.83
FATHMM_MKL	Uncertain	0.97	D
LIST_S2	Benign	0.79	.;T;T;T
M_CAP	Pathogenic	0.46	D
MetaRNN	Pathogenic	0.97	D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	4.5	H;H;.;.
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.49	T
PROVEAN	Uncertain	-3.8	.;D;.;.
REVEL	Pathogenic	0.95
Sift	Uncertain	0.0030	.;D;.;.
Sift4G	Uncertain	0.044	.;D;D;D
Polyphen		1.0	D;D;.;.
Vest4		0.83, 0.86, 0.93
MutPred		0.88		Gain of disorder (P = 0.115);Gain of disorder (P = 0.115);Gain of disorder (P = 0.115);Gain of disorder (P = 0.115);
MVP		1.0
MPC		1.3
ClinPred		1.0	D
GERP RS		5.5
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Varity_R		0.88
gMVP		0.96

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs1555631387; hg19: chr18-29175088;