chr2-74378104-C-T

Variant names:

• chr2-74378104-C-T
• rs121909342
• NM_004082.5:c.175G>A

Variant summary

Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PM1 PM2 PP3 PP5_Moderate

The NM_004082.5(DCTN1):​c.175G>A​(p.Gly59Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 13/23 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★). Synonymous variant affecting the same amino acid position (i.e. G59G) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 32)
• Consequence: DCTN1 NM_004082.5 missense
• Clinical Significance: Pathogenic criteria provided, single submitter P:2 U:2
• Conservation: PhyloP100: 7.81

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

Verdict is Likely_pathogenic. Variant got 7 ACMG points.

• PM1: In a domain CAP-Gly (size 42) in uniprot entity DCTN1_HUMAN there are 11 pathogenic changes around while only 1 benign (92%) in NM_004082.5
• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 2-74378104-C-T is Pathogenic according to our data. Variant chr2-74378104-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 8401.Status of the report is criteria_provided_single_submitter, 1 stars. Variant chr2-74378104-C-T is described in Lovd as [Pathogenic]. Variant chr2-74378104-C-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
DCTN1	NM_004082.5	c.175G>A	p.Gly59Ser	missense_variant	Exon 2 of 32	ENST00000628224.3	NP_004073.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
DCTN1	ENST00000628224.3	c.175G>A	p.Gly59Ser	missense_variant	Exon 2 of 32	5	NM_004082.5	ENSP00000487279.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2 Uncertain:2

Revision: criteria provided, single submitter

Submissions by phenotype

Neuronopathy, distal hereditary motor, type 7B Pathogenic:1

Mar 31, 2009

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

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

Oct 27, 2020

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

For these reasons, this variant has been classified as Pathogenic. Experimental studies have shown that this missense change reduces the ability of the dynactin protein to properly bind microtubules and leads to protein aggregation and loss of motor neurons (PMID: 12627231, 19279216, 16505168, 23143281). Additionally, several mouse models have recapitulated the disease phenotype observed in individuals carrying this variant. (PMID: 18364389, 18094236). This variant has been reported to segregate with hereditary motor neuropathy, type 7B in a single family and has also been reported in additional, unrelated affected individuals (PMID: 12627231, 27573046 ). ClinVar contains an entry for this variant (Variation ID: 8401). This variant is not present in population databases (ExAC no frequency). This sequence change replaces glycine with serine at codon 59 of the DCTN1 protein (p.Gly59Ser). The glycine residue is highly conserved and there is a small physicochemical difference between glycine and serine. -

Hereditary motor neuron disease Uncertain:1

-

Inherited Neuropathy Consortium

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Perry syndrome Uncertain:1

Jan 06, 2016

Inherited Neuropathy Consortium Ii, University Of Miami

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.58	D
BayesDel_noAF	Pathogenic	0.59
CADD	Pathogenic	34
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.79	D;.;D;.;D;.;.;D;D;.;D;D;.
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.90
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	1.0	D;D;D;D;.;D;D;D;D;D;.;D;D
M_CAP	Pathogenic	0.92	D
MetaRNN	Pathogenic	0.99	D;D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	0.89	D
MutationAssessor	Pathogenic	4.2	H;H;.;.;.;H;.;.;.;.;.;.;.
PrimateAI	Pathogenic	0.86	D
PROVEAN	Pathogenic	-5.4	D;D;.;D;D;D;D;D;D;D;D;D;D
REVEL	Pathogenic	0.99
Sift	Pathogenic	0.0	D;D;.;D;D;D;D;D;D;D;D;D;D
Sift4G	Pathogenic	0.0	D;D;D;D;D;D;.;.;D;.;D;D;D
Polyphen		1.0	D;.;.;.;.;.;.;.;.;.;.;.;.
Vest4		0.99
MutPred		0.97		Loss of methylation at K56 (P = 0.083);Loss of methylation at K56 (P = 0.083);.;.;.;Loss of methylation at K56 (P = 0.083);.;.;.;.;.;.;.;
MVP		1.0
MPC		1.6
ClinPred		1.0	D
GERP RS		5.1
Varity_R		0.99
gMVP		0.94

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.76		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.76		Position offset: 4

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs121909342; hg19: chr2-74605231;