NM_006073.4:c.1996G>A

Variant names:

• chr6-123224111-C-T
• rs748450167
• NM_006073.4:c.1996G>A

Variant summary

Our verdict is Likely benign. The variant received -4 ACMG points: 0P and 4B. BP4_Strong

The NM_006073.4(TRDN):​c.1996G>A​(p.Ala666Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000807 in 1,609,964 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/20 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A666P) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.000026 (0 hom., cov: 31)
  • Exomes 𝑓: 0.0000062 (0 hom.)
• Consequence: TRDN NM_006073.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: -0.437
• Publications: 0 publications found

Genes affected

TRDN (HGNC:12261): (triadin) This gene encodes an integral membrane protein found in skeletal and cardiac muscle. The encoded protein plays a role in skeletal muscle excitation-contraction coupling as part of the calcium release complex and is required for normal skeletal muscle strength. This protein indirectly links triads and microtubules in skeletal muscle. Mutations in this gene are associated with cardiac arrythmia syndrome and some variants in this gene may be associated with sudden cardiac death. [provided by RefSeq, May 2022]

TRDN Gene-Disease associations (from GenCC):

• catecholaminergic polymorphic ventricular tachycardia

  Inheritance: AD, AR Classification: DEFINITIVE, SUPPORTIVE Submitted by: Orphanet, ClinGen
• catecholaminergic polymorphic ventricular tachycardia 5

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P, Genomics England PanelApp
• familial long QT syndrome

  Inheritance: AR Classification: STRONG Submitted by: G2P
• long QT syndrome

  Inheritance: AR Classification: STRONG Submitted by: ClinGen

ACMG classification

Our verdict: Likely_benign. The variant received -4 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.060114533).

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_006073.4. 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
	TRDN	NM_006073.4	MANE Select	c.1996G>A	p.Ala666Thr	missense	Exon 39 of 41	NP_006064.2

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TRDN	ENST00000334268.9	TSL:1 MANE Select	c.1996G>A	p.Ala666Thr	missense	Exon 39 of 41	ENSP00000333984.5

Frequencies

GnomAD3 genomes AF: 0.0000264 AC: 4 AN: 151294 Hom.: 0 Cov.: 31

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000265

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: 0.00

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000201 AC: 5 AN: 248286 AF XY: 0.0000297

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.000116

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000888

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000617 AC: 9 AN: 1458670 Hom.: 0 Cov.: 31 AF XY: 0.00000551 AC XY: 4 AN XY: 725644

African (AFR) AF: 0.00 AC: 0 AN: 33256

American (AMR) AF: 0.000157 AC: 7 AN: 44606

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26024

East Asian (EAS) AF: 0.00 AC: 0 AN: 39630

South Asian (SAS) AF: 0.0000116 AC: 1 AN: 86104

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53138

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5744

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1110010

Other (OTH) AF: 0.0000166 AC: 1 AN: 60158

GnomAD4 genome AF: 0.0000264 AC: 4 AN: 151294 Hom.: 0 Cov.: 31 AF XY: 0.0000406 AC XY: 3 AN XY: 73808

African (AFR) AF: 0.00 AC: 0 AN: 41284

American (AMR) AF: 0.000265 AC: 4 AN: 15118

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3464

East Asian (EAS) AF: 0.00 AC: 0 AN: 5126

South Asian (SAS) AF: 0.00 AC: 0 AN: 4800

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10454

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 312

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 67744

Other (OTH) AF: 0.00 AC: 0 AN: 2080

Alfa AF: 0.00 Hom.: 0

ExAC AF: 0.0000249 AC: 3

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Catecholaminergic polymorphic ventricular tachycardia 1 Uncertain:1

Jul 17, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces alanine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 666 of the TRDN protein (p.Ala666Thr). This variant is present in population databases (rs748450167, gnomAD 0.01%). This variant has not been reported in the literature in individuals affected with TRDN-related conditions. ClinVar contains an entry for this variant (Variation ID: 532359). Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Not Available"; PolyPhen-2: "Benign"; Align-GVGD: "Not Available". The threonine amino acid residue is found in multiple mammalian species, which suggests that this missense change does not adversely affect protein function. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance.

Cardiovascular phenotype Uncertain:1

Aug 31, 2025

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.A666T variant (also known as c.1996G>A), located in coding exon 39 of the TRDN gene, results from a G to A substitution at nucleotide position 1996. The alanine at codon 666 is replaced by threonine, an amino acid with similar properties. This amino acid position is conserved. In addition, this alteration is predicted to be tolerated by in silico analysis. Based on the available evidence, the clinical significance of this variant remains unclear.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.081
BayesDel_addAF	Benign	-0.51	T
BayesDel_noAF	Benign	-0.72
CADD	Benign	9.9
DANN	Benign	0.95
DEOGEN2	Benign	0.083	T
Eigen	Benign	-1.2
Eigen_PC	Benign	-1.2
FATHMM_MKL	Benign	0.049	N
LIST_S2	Benign	0.45	T
M_CAP	Benign	0.0045	T
MetaRNN	Benign	0.060	T
MetaSVM	Benign	-0.91	T
MutationAssessor	Benign	0.81	L
PhyloP100		-0.44
PrimateAI	Benign	0.26	T
REVEL	Benign	0.016
Sift4G	Benign	0.46	T
Polyphen		0.013	B
Vest4		0.18
MutPred		0.21		Gain of relative solvent accessibility (P = 0.0082)
MVP		0.014
ClinPred		0.013	T
GERP RS		1.0
Varity_R		0.028
gMVP		0.033
Mutation Taster		=97/3	polymorphism

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: rs748450167; hg19: chr6-123545256;