3-123752475-C-G

Variant names:

• chr3-123752475-C-G
• rs139000120
• NM_053025.4:c.229G>C

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM2

The NM_053025.4(MYLK):​c.229G>C​(p.Gly77Arg) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. 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. G77S) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: MYLK NM_053025.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.92
• Publications: 0 publications found

Genes affected

MYLK (HGNC:7590): (myosin light chain kinase) This gene, a muscle member of the immunoglobulin gene superfamily, encodes myosin light chain kinase which is a calcium/calmodulin dependent enzyme. This kinase phosphorylates myosin regulatory light chains to facilitate myosin interaction with actin filaments to produce contractile activity. This gene encodes both smooth muscle and nonmuscle isoforms. In addition, using a separate promoter in an intron in the 3' region, it encodes telokin, a small protein identical in sequence to the C-terminus of myosin light chain kinase, that is independently expressed in smooth muscle and functions to stabilize unphosphorylated myosin filaments. A pseudogene is located on the p arm of chromosome 3. Four transcript variants that produce four isoforms of the calcium/calmodulin dependent enzyme have been identified as well as two transcripts that produce two isoforms of telokin. Additional variants have been identified but lack full length transcripts. [provided by RefSeq, Jul 2008]

MYLK Gene-Disease associations (from GenCC):

• aortic aneurysm, familial thoracic 7

  Inheritance: AD Classification: STRONG, MODERATE Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics
• familial thoracic aortic aneurysm and aortic dissection

  Inheritance: AD Classification: STRONG, SUPPORTIVE Submitted by: Orphanet, ClinGen
• megacystis-microcolon-intestinal hypoperistalsis syndrome 1

  Inheritance: AR Classification: STRONG Submitted by: G2P
• connective tissue disorder

  Inheritance: AD Classification: MODERATE Submitted by: Genomics England PanelApp
• megacystis-microcolon-intestinal hypoperistalsis syndrome

  Inheritance: AD, AR Classification: SUPPORTIVE, LIMITED Submitted by: Orphanet, Ambry Genetics

ENSG00000304368 (HGNC:):

ACMG classification

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MYLK	NM_053025.4	c.229G>C	p.Gly77Arg	missense_variant	Exon 5 of 34	ENST00000360304.8	NP_444253.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MYLK	ENST00000360304.8	c.229G>C	p.Gly77Arg	missense_variant	Exon 5 of 34	5	NM_053025.4	ENSP00000353452.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Aortic aneurysm, familial thoracic 7 Uncertain:1

Jul 07, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt MYLK protein function. This variant has not been reported in the literature in individuals affected with MYLK-related conditions. This variant is not present in population databases (ExAC no frequency). This sequence change replaces glycine with arginine at codon 77 of the MYLK protein (p.Gly77Arg). The glycine residue is highly conserved and there is a moderate physicochemical difference between glycine and arginine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.56
BayesDel_addAF	Benign	-0.027	T
BayesDel_noAF	Benign	-0.28
CADD	Benign	22
DANN	Uncertain	1.0
DEOGEN2	Benign	0.30	.;.;.;T;.;T
Eigen	Uncertain	0.33
Eigen_PC	Uncertain	0.39
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Uncertain	0.94	.;D;D;D;.;.
M_CAP	Benign	0.016	T
MetaRNN	Uncertain	0.46	T;T;T;T;T;T
MetaSVM	Benign	-1.0	T
MutationAssessor	Benign	1.7	L;L;L;L;L;L
PhyloP100		3.9
PrimateAI	Benign	0.43	T
PROVEAN	Benign	-2.3	N;.;N;N;N;N
REVEL	Benign	0.15
Sift	Benign	0.51	T;.;T;T;T;T
Sift4G	Uncertain	0.0070	D;D;D;D;D;D
Polyphen		0.31	B;D;B;D;D;D
Vest4		0.55
MutPred		0.62		Gain of MoRF binding (P = 0.0364);Gain of MoRF binding (P = 0.0364);Gain of MoRF binding (P = 0.0364);Gain of MoRF binding (P = 0.0364);Gain of MoRF binding (P = 0.0364);Gain of MoRF binding (P = 0.0364);
MVP		0.72
MPC		0.73
ClinPred		0.89	D
GERP RS		4.6
Varity_R		0.093
gMVP		0.42
Mutation Taster		=88/12	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: rs139000120; hg19: chr3-123471322;