chr3-123666266-T-C

Position:

• chr3-123666266-T-C

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 3P and 3B. PM2 PP2 BP4_Moderate BP6

The NM_053025.4(MYLK):​c.3784A>G​(p.Thr1262Ala) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,894 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 16/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: MYLK NM_053025.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1 B:1
• Conservation: PhyloP100: 0.148

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]

ACMG classification

Verdict is Uncertain_significance. Variant got 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), MYLK. . Gene score misZ 1.1317 (greater than the threshold 3.09). Trascript score misZ 3.1503 (greater than threshold 3.09). GenCC has associacion of gene with familial thoracic aortic aneurysm and aortic dissection, connective tissue disorder, megacystis-microcolon-intestinal hypoperistalsis syndrome, aortic aneurysm, familial thoracic 7.
• BP4: Computational evidence support a benign effect (MetaRNN=0.10960588).
• BP6: Variant 3-123666266-T-C is Benign according to our data. Variant chr3-123666266-T-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 471727.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=1, Uncertain_significance=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
MYLK	NM_053025.4	c.3784A>G	p.Thr1262Ala	missense_variant	22/34	ENST00000360304.8	NP_444253.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
MYLK	ENST00000360304.8	c.3784A>G	p.Thr1262Ala	missense_variant	22/34	5	NM_053025.4	ENSP00000353452	P4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461894 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 727248

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

Bravo AF: 0.00000378

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:1 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Aortic aneurysm, familial thoracic 7 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jun 30, 2022

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. ClinVar contains an entry for this variant (Variation ID: 471727). This variant has not been reported in the literature in individuals affected with MYLK-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces threonine, which is neutral and polar, with alanine, which is neutral and non-polar, at codon 1262 of the MYLK protein (p.Thr1262Ala). -

Familial thoracic aortic aneurysm and aortic dissection Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Ambry Genetics

Aug 24, 2022

This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.21
BayesDel_addAF	Benign	-0.19	T
BayesDel_noAF	Benign	-0.52
CADD	Benign	0.056
DANN	Benign	0.27
DEOGEN2	Benign	0.22	.;.;.;T;.;T;T
Eigen	Benign	-1.4
Eigen_PC	Benign	-1.4
FATHMM_MKL	Benign	0.015	N
LIST_S2	Benign	0.61	.;T;T;T;.;.;T
M_CAP	Benign	0.0076	T
MetaRNN	Benign	0.11	T;T;T;T;T;T;T
MetaSVM	Benign	-0.99	T
MutationAssessor	Benign	0.090	N;.;N;N;.;N;.
MutationTaster	Benign	1.0	N;N;N;N;N;N
PrimateAI	Benign	0.35	T
PROVEAN	Benign	-0.24	N;.;N;N;N;N;N
REVEL	Benign	0.16
Sift	Benign	1.0	T;.;T;T;T;T;T
Sift4G	Benign	1.0	T;T;T;T;T;T;.
Polyphen		0.0	B;B;B;B;B;B;.
Vest4		0.057
MutPred		0.53		Gain of catalytic residue at T1262 (P = 0.0567);.;Gain of catalytic residue at T1262 (P = 0.0567);Gain of catalytic residue at T1262 (P = 0.0567);.;Gain of catalytic residue at T1262 (P = 0.0567);.;
MVP		0.41
MPC		0.15
ClinPred		0.020	T
GERP RS		-3.8
Varity_R		0.037
gMVP		0.088

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: rs1553788596; hg19: chr3-123385113;