chr3-123752313-G-A

Variant names:

• chr3-123752313-G-A
• rs140559450
• NM_053025.4:c.373+18C>T

Variant summary

Our verdict is Benign. The variant received -16 ACMG points: 0P and 16B. BP4_Strong BP6_Very_Strong BS1

The NM_053025.4(MYLK):​c.373+18C>T variant causes a intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000884 in 1,613,314 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★★).

• Frequency:
  • Genomes: 𝑓 0.00072 (0 hom., cov: 32)
  • Exomes 𝑓: 0.00090 (0 hom.)
• Consequence: MYLK NM_053025.4 intron
• Clinical Significance: Benign/Likely benign criteria provided, multiple submitters, no conflicts B:8
• Conservation: PhyloP100: -0.318
• 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: Benign. The variant received -16 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.91).
• BP6: Variant 3-123752313-G-A is Benign according to our data. Variant chr3-123752313-G-A is described in ClinVar as Benign/Likely_benign. ClinVar VariationId is 262280.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• BS1: Variant frequency is greater than expected in population nfe. GnomAd4 allele frequency = 0.000722 (110/152274) while in subpopulation NFE AF = 0.00137 (93/68020). AF 95% confidence interval is 0.00114. There are 0 homozygotes in GnomAd4. There are 50 alleles in the male GnomAd4 subpopulation. Median coverage is 32. This position passed quality control check.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MYLK	NM_053025.4	c.373+18C>T		intron_variant	Intron 5 of 33	ENST00000360304.8	NP_444253.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MYLK	ENST00000360304.8	c.373+18C>T		intron_variant	Intron 5 of 33	5	NM_053025.4	ENSP00000353452.3

Frequencies

GnomAD3 genomes AF: 0.000723 AC: 110 AN: 152156 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.000314

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000196

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: 0.00137

Gnomad OTH AF: 0.000478

GnomAD2 exomes AF: 0.000495 AC: 124 AN: 250508 AF XY: 0.000517

Gnomad AFR exome AF: 0.000123

Gnomad AMR exome AF: 0.000145

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000544

Gnomad FIN exome AF: 0.0000462

Gnomad NFE exome AF: 0.00100

Gnomad OTH exome AF: 0.000327

GnomAD4 exome AF: 0.000901 AC: 1316 AN: 1461040 Hom.: 0 Cov.: 32 AF XY: 0.000894 AC XY: 650 AN XY: 726864

African (AFR) AF: 0.000179 AC: 6 AN: 33448

American (AMR) AF: 0.000134 AC: 6 AN: 44724

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

East Asian (EAS) AF: 0.0000252 AC: 1 AN: 39694

South Asian (SAS) AF: 0.0000116 AC: 1 AN: 86206

European-Finnish (FIN) AF: 0.0000749 AC: 4 AN: 53406

Middle Eastern (MID) AF: 0.000189 AC: 1 AN: 5282

European-Non Finnish (NFE) AF: 0.00114 AC: 1270 AN: 1111808

Other (OTH) AF: 0.000447 AC: 27 AN: 60336

GnomAD4 genome AF: 0.000722 AC: 110 AN: 152274 Hom.: 0 Cov.: 32 AF XY: 0.000672 AC XY: 50 AN XY: 74458

African (AFR) AF: 0.000313 AC: 13 AN: 41556

American (AMR) AF: 0.000196 AC: 3 AN: 15296

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3468

East Asian (EAS) AF: 0.00 AC: 0 AN: 5164

South Asian (SAS) AF: 0.00 AC: 0 AN: 4828

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10624

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 294

European-Non Finnish (NFE) AF: 0.00137 AC: 93 AN: 68020

Other (OTH) AF: 0.000473 AC: 1 AN: 2112

Alfa AF: 0.000935 Hom.: 0

Bravo AF: 0.000771

ClinVar

Significance: Benign/Likely benign

Submissions summary: Benign:8

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Benign:5

-

Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center

Significance: Benign

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

-

Genome Diagnostics Laboratory, Amsterdam University Medical Center

Significance: Benign

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Sep 08, 2020

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: MYLK c.373+18C>T alters a non-conserved nucleotide located close to a canonical splice site and therefore could affect mRNA splicing, leading to a significantly altered protein sequence. 4/4 computational tools predict no significant impact on normal splicing. However, these predictions have yet to be confirmed by functional studies. The variant allele was found at a frequency of 0.00049 in 250508 control chromosomes, predominantly at a frequency of 0.001 within the Non-Finnish European subpopulation in the gnomAD database. The observed variant frequency within Non-Finnish European control individuals in the gnomAD database is approximately 20 fold of the estimated maximal expected allele frequency for a pathogenic variant in MYLK causing Thoracic Aortic Aneurysms and Dissections phenotype (5e-05), strongly suggesting that the variant is a benign polymorphism found primarily in populations of Non-Finnish European origin. To our knowledge, no occurrence of c.373+18C>T in individuals affected with Thoracic Aortic Aneurysms and Dissections and no experimental evidence demonstrating its impact on protein function have been reported. One ClinVar submitter (evaluation after 2014) cite the variant as likely benign. Based on the evidence outlined above, the variant was classified as benign. -

-

PreventionGenetics, part of Exact Sciences

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Nov 06, 2017

GeneDx

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is considered likely benign or benign based on one or more of the following criteria: it is a conservative change, it occurs at a poorly conserved position in the protein, it is predicted to be benign by multiple in silico algorithms, and/or has population frequency not consistent with disease. -

Aortic aneurysm, familial thoracic 7 Benign:1

Feb 03, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Aortic aneurysm, familial thoracic 7;C5542316:Megacystis-microcolon-intestinal hypoperistalsis syndrome 1 Benign:1

Dec 16, 2021

Fulgent Genetics, Fulgent Genetics

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not provided Benign:1

Oct 14, 2024

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.91
CADD	Benign	0.27
DANN	Benign	0.42
PhyloP100		-0.32
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Mutation Taster		=100/0	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: rs140559450; hg19: chr3-123471160;