18-31592942-C-T

Position:

• chr18-31592942-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM1 PM2 PP3

The NM_000371.4(TTR):​c.116C>T​(p.Ala39Val) variant causes a missense change. The variant allele was found at a frequency of 0.000000684 in 1,461,796 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: TTR NM_000371.4 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 4.41

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 Uncertain_significance. Variant got 5 ACMG points.

• PM1: In a chain Transthyretin (size 126) in uniprot entity TTHY_HUMAN there are 141 pathogenic changes around while only 6 benign (96%) in NM_000371.4
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.795

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TTR	NM_000371.4	c.116C>T	p.Ala39Val	missense_variant	2/4	ENST00000237014.8	NP_000362.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TTR	ENST00000237014.8	c.116C>T	p.Ala39Val	missense_variant	2/4	1	NM_000371.4	ENSP00000237014	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461796 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 727206

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: 0.00

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.46
BayesDel_addAF	Pathogenic	0.27	D
BayesDel_noAF	Pathogenic	0.15
CADD	Uncertain	24
DANN	Pathogenic	1.0
DEOGEN2	Uncertain	0.76	D;D;T;.
Eigen	Uncertain	0.45
Eigen_PC	Uncertain	0.38
FATHMM_MKL	Uncertain	0.85	D
LIST_S2	Uncertain	0.90	.;D;D;D
M_CAP	Pathogenic	0.45	D
MetaRNN	Pathogenic	0.80	D;D;D;D
MetaSVM	Pathogenic	0.97	D
MutationAssessor	Uncertain	2.5	M;M;.;.
MutationTaster	Benign	1.0	D
PrimateAI	Benign	0.47	T
PROVEAN	Benign	-1.8	.;N;.;.
REVEL	Pathogenic	0.71
Sift	Uncertain	0.0040	.;D;.;.
Sift4G	Uncertain	0.012	.;D;D;D
Polyphen		0.98	D;D;.;.
Vest4		0.38, 0.40, 0.66
MutPred		0.49		Gain of methylation at K35 (P = 0.1051);Gain of methylation at K35 (P = 0.1051);Gain of methylation at K35 (P = 0.1051);Gain of methylation at K35 (P = 0.1051);
MVP		1.0
MPC		0.66
ClinPred		0.97	D
GERP RS		4.8
Varity_R		0.81
gMVP		0.97

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: rs11541795; hg19: chr18-29172905;