NM_053025.4:c.256C>G

Variant names:

• chr3-123752448-G-C
• rs368822172
• NM_053025.4:c.256C>G

Variant summary

Our verdict is Uncertain significance. The variant received 1 ACMG points: 1P and 0B. PP3

The NM_053025.4(MYLK):​c.256C>G​(p.Arg86Gly) variant causes a missense change. The variant allele was found at a frequency of 0.0000217 in 1,614,042 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic 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. R86W) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000023 (0 hom.)
• Consequence: MYLK NM_053025.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 5.22
• Publications: 2 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 1 ACMG points.

• PP3: MetaRNN computational evidence supports a deleterious effect, 0.812

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_053025.4. 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
	MYLK	NM_053025.4	MANE Select	c.256C>G	p.Arg86Gly	missense	Exon 5 of 34	NP_444253.3
	MYLK	NM_053027.4		c.256C>G	p.Arg86Gly	missense	Exon 5 of 33	NP_444255.3
	MYLK	NM_053026.4		c.256C>G	p.Arg86Gly	missense	Exon 5 of 33	NP_444254.3

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MYLK	ENST00000360304.8	TSL:5 MANE Select	c.256C>G	p.Arg86Gly	missense	Exon 5 of 34	ENSP00000353452.3
	MYLK	ENST00000464489.5	TSL:1	n.166-12447C>G		intron	N/A	ENSP00000417798.1
	MYLK	ENST00000687848.1		c.286C>G	p.Arg96Gly	missense	Exon 3 of 32	ENSP00000508761.1

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152168 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000241

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

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

GnomAD4 exome AF: 0.0000233 AC: 34 AN: 1461874 Hom.: 0 Cov.: 32 AF XY: 0.0000261 AC XY: 19 AN XY: 727240

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39698

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53410

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5764

European-Non Finnish (NFE) AF: 0.0000306 AC: 34 AN: 1112008

Other (OTH) AF: 0.00 AC: 0 AN: 60396

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152168 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74334

African (AFR) AF: 0.0000241 AC: 1 AN: 41430

American (AMR) AF: 0.00 AC: 0 AN: 15286

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3466

East Asian (EAS) AF: 0.00 AC: 0 AN: 5188

South Asian (SAS) AF: 0.00 AC: 0 AN: 4822

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10620

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68036

Other (OTH) AF: 0.00 AC: 0 AN: 2092

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Aortic aneurysm, familial thoracic 7 Uncertain:2

Nov 20, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces arginine, which is basic and polar, with glycine, which is neutral and non-polar, at codon 86 of the MYLK protein (p.Arg86Gly). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with MYLK-related conditions. ClinVar contains an entry for this variant (Variation ID: 903432). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is not expected to disrupt MYLK protein function with a negative predictive value of 95%. 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.

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease.

Familial thoracic aortic aneurysm and aortic dissection Uncertain:1

Sep 25, 2023

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.256C>G (p.R86G) alteration is located in exon 5 (coding exon 2) of the MYLK gene. This alteration results from a C to G substitution at nucleotide position 256, causing the arginine (R) at amino acid position 86 to be replaced by a glycine (G). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.43
BayesDel_addAF	Benign	-0.022	T
BayesDel_noAF	Benign	-0.27
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Benign	0.24	T
Eigen	Uncertain	0.23
Eigen_PC	Uncertain	0.25
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Uncertain	0.93	D
M_CAP	Benign	0.022	T
MetaRNN	Pathogenic	0.81	D
MetaSVM	Benign	-1.1	T
MutationAssessor	Benign	1.1	L
PhyloP100		5.2
PrimateAI	Uncertain	0.49	T
PROVEAN	Benign	-1.9	N
REVEL	Benign	0.21
Sift	Benign	0.45	T
Sift4G	Pathogenic	0.0	D
Polyphen		0.72	P
Vest4		0.70
MutPred		0.64		Loss of MoRF binding (P = 0.0575)
MVP		0.68
MPC		0.25
ClinPred		0.81	D
GERP RS		4.3
Varity_R		0.15
gMVP		0.42
Mutation Taster		=78/22	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: rs368822172; hg19: chr3-123471295;