2-74370670-G-T

Variant names:

• chr2-74370670-G-T
• rs200952455
• NM_004082.5:c.999C>A

Variant summary

Our verdict is Likely benign. The variant received -6 ACMG points: 2P and 8B. PM2 BP4_Strong BS2

The NM_004082.5(DCTN1):​c.999C>A​(p.Asp333Glu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000342 in 1,461,880 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 17/23 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Another nucleotide change resulting in the same amino acid substitution has been previously reported as Likely benign in ClinVar. Synonymous variant affecting the same amino acid position (i.e. D333D) has been classified as Benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000034 (0 hom.)
• Consequence: DCTN1 NM_004082.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: -4.05

Genes affected

DCTN1 (HGNC:2711): (dynactin subunit 1) This gene encodes the largest subunit of dynactin, a macromolecular complex consisting of 10 subunits ranging in size from 22 to 150 kD. Dynactin binds to both microtubules and cytoplasmic dynein. Dynactin is involved in a diverse array of cellular functions, including ER-to-Golgi transport, the centripetal movement of lysosomes and endosomes, spindle formation, chromosome movement, nuclear positioning, and axonogenesis. This subunit interacts with dynein intermediate chain by its domains directly binding to dynein and binds to microtubules via a highly conserved glycine-rich cytoskeleton-associated protein (CAP-Gly) domain in its N-terminus. Alternative splicing of this gene results in multiple transcript variants encoding distinct isoforms. Mutations in this gene cause distal hereditary motor neuronopathy type VIIB (HMN7B) which is also known as distal spinal and bulbar muscular atrophy (dSBMA). [provided by RefSeq, Oct 2008]

ACMG classification

Our verdict: Likely_benign. The variant received -6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.0118254125).
• BS2: High AC in GnomAdExome4 at 5 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
DCTN1	NM_004082.5	c.999C>A	p.Asp333Glu	missense_variant	Exon 10 of 32	ENST00000628224.3	NP_004073.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
DCTN1	ENST00000628224.3	c.999C>A	p.Asp333Glu	missense_variant	Exon 10 of 32	5	NM_004082.5	ENSP00000487279.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.00000398 AC: 1 AN: 251458 AF XY: 0.00

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000879

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000342 AC: 5 AN: 1461880 Hom.: 0 Cov.: 34 AF XY: 0.00000275 AC XY: 2 AN XY: 727242

Gnomad4 AFR exome AF: 0.00 AC: 0 AN: 33480

Gnomad4 AMR exome AF: 0.00 AC: 0 AN: 44724

Gnomad4 ASJ exome AF: 0.00 AC: 0 AN: 26136

Gnomad4 EAS exome AF: 0.0000252 AC: 1 AN: 39700

Gnomad4 SAS exome AF: 0.0000232 AC: 2 AN: 86258

Gnomad4 FIN exome AF: 0.00 AC: 0 AN: 53406

Gnomad4 NFE exome AF: 0.00000180 AC: 2 AN: 1112012

Gnomad4 Remaining exome AF: 0.00 AC: 0 AN: 60396

GnomAD4 genome Cov.: 32

EpiCase AF: 0.00

EpiControl AF: 0.0000593

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Neuronopathy, distal hereditary motor, type 7B;C1862939:Amyotrophic lateral sclerosis type 1;C1868594:Perry syndrome Uncertain:1

Feb 19, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is present in population databases (no rsID available, gnomAD 0.0009%). This sequence change replaces aspartic acid, which is acidic and polar, with glutamic acid, which is acidic and polar, at codon 333 of the DCTN1 protein (p.Asp333Glu). This missense change has been observed in individual(s) with DCTN1-related conditions (PMID: 23143281). Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Tolerated"; PolyPhen-2: "Benign"; Align-GVGD: "Class C0". The glutamic acid amino acid residue is found in multiple mammalian species, which suggests that this missense change does not adversely affect protein function. Experimental studies have shown that this missense change does not substantially affect DCTN1 function (PMID: 23143281). 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.080
BayesDel_addAF	Benign	-0.18	T
BayesDel_noAF	Benign	-0.49
CADD	Benign	0.0010
DANN	Benign	0.66
DEOGEN2	Benign	0.12	T;.;T;.;.;.;T;.
Eigen	Benign	-2.0
Eigen_PC	Benign	-1.9
FATHMM_MKL	Benign	0.025	N
LIST_S2	Benign	0.81	T;T;T;T;T;T;.;T
M_CAP	Benign	0.031	D
MetaRNN	Benign	0.012	T;T;T;T;T;T;T;T
MetaSVM	Benign	-0.83	T
MutationAssessor	Benign	-1.5	N;.;.;.;.;.;.;.
PrimateAI	Benign	0.48	T
PROVEAN	Benign	1.7	N;N;.;.;N;N;N;N
REVEL	Benign	0.12
Sift	Benign	1.0	T;T;.;.;T;T;T;T
Sift4G	Benign	1.0	T;T;T;T;T;T;T;T
Polyphen		0.0010	B;.;.;B;.;.;.;.
Vest4		0.11
MutPred		0.12		Loss of phosphorylation at T336 (P = 0.2342);.;.;.;.;.;.;.;
MVP		0.39
MPC		0.55
ClinPred		0.038	T
GERP RS		-11
Varity_R		0.025
gMVP		0.058
Mutation Taster		=95/5	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

Publications

LitVar

Other links and lift over

dbSNP: rs200952455; hg19: chr2-74597797;