chr22-50076840-CTGAG-C

Variant names:

Variant summary

Our verdict is Pathogenic. The variant received 20 ACMG points: 20P and 0B. PVS1PM2PP3_ModeratePP5_Very_Strong

The NM_015166.4(MLC1):c.594_597delCTCA(p.Tyr198fs) variant causes a frameshift, splice region change. The variant allele was found at a frequency of 0.0000031 in 1,613,596 control chromosomes in the GnomAD database, with no homozygous occurrence. 1/1 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. Y198Y) has been classified as Benign. Variant results in nonsense mediated mRNA decay.

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 33)

Exomes 𝑓: 0.0000027 ( 0 hom. )

Consequence

MLC1
NM_015166.4 frameshift, splice_region

Scores

Not classified

Clinical Significance

Pathogenic criteria provided, multiple submitters, no conflicts P:7

Conservation

PhyloP100: 6.89

Publications

4 publications found

Variant links:

Genes affected

MLC1 (HGNC:17082): (modulator of VRAC current 1) The function of this gene product is unknown; however, homology to other proteins suggests that it may be an integral membrane transporter. Mutations in this gene have been associated with megalencephalic leukoencephalopathy with subcortical cysts, an autosomal recessive neurological disorder. Alternatively spliced transcript variants encoding different isoforms have been identified. [provided by RefSeq, Jul 2008]

MLC1 Gene-Disease associations (from GenCC):

megalencephalic leukoencephalopathy with subcortical cysts 1
Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, G2P, Myriad Women’s Health
megalencephalic leukoencephalopathy with subcortical cysts
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

MLC1 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 20 ACMG points.

PVS1

Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.

PM2

Very rare variant in population databases, with high coverage;

PP3

Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.

PP5

Variant 22-50076840-CTGAG-C is Pathogenic according to our data. Variant chr22-50076840-CTGAG-C is described in ClinVar as Pathogenic. ClinVar VariationId is 4720.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MLC1	NM_015166.4 link	c.594_597delCTCA	p.Tyr198fs	frameshift_variant, splice_region_variant	Exon 7 of 12	ENST00000311597.10	NP_055981.1	Q15049-1A0A024R4V4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	UniProt
MLC1	ENST00000311597.10 link	c.594_597delCTCA	p.Tyr198fs	frameshift_variant, splice_region_variant	Exon 7 of 12	1	NM_015166.4	ENSP00000310375.6	Q15049-1
MLC1	ENST00000395876.6 link	c.594_597delCTCA	p.Tyr198fs	frameshift_variant, splice_region_variant	Exon 7 of 12	1		ENSP00000379216.2	Q15049-1
MLC1	ENST00000442311.1 link	c.504_507delCTCA	p.Tyr168fs	frameshift_variant, splice_region_variant	Exon 6 of 8	5		ENSP00000401385.1	A6PVC3

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152208

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

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:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.00000796

AC:

AN:

251176

AF XY:

0.00000737

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000176

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000274

AC:

AN:

1461388

Hom.:

AF XY:

0.00000138

AC XY:

AN XY:

727026

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33468

American (AMR)

AF:

0.00

AC:

AN:

44716

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26132

East Asian (EAS)

AF:

0.00

AC:

AN:

39696

South Asian (SAS)

AF:

0.00

AC:

AN:

86242

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53354

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5762

European-Non Finnish (NFE)

AF:

0.00000360

AC:

AN:

1111648

Other (OTH)

AF:

0.00

AC:

AN:

60370

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.513

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.00000657

AC:

AN:

152208

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

74352

show subpopulations

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00

AC:

AN:

41456

American (AMR)

AF:

0.00

AC:

AN:

15282

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5198

South Asian (SAS)

AF:

0.00

AC:

AN:

4830

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10612

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.0000147

AC:

AN:

68038

Other (OTH)

AF:

0.00

AC:

AN:

2092

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.275

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.00000378

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:7

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Megalencephalic leukoencephalopathy with subcortical cysts 1

Pathogenic:5

Mar 01, 2002

OMIM

Significance:Pathogenic

Review Status:no assertion criteria provided

Collection Method:literature only

- -

Feb 09, 2021

Molecular Diagnostics Lab, Nemours Children's Health, Delaware

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant (c.593_596del, p.Tyr198*) predicts a deletion resulting in a stop codon at tyrosine 198. It has been observed at very low frequency in population databases (gnomAD) and has been described in the literature (PMID 11254442). It was found in trans with a likely pathogenic variant (c.833A>G, p.Tyr278Cys) in an affected individual. -

Myelin Disorders Clinic-Children's Medical Center/Medical Genetics Lab-Tarbiat Modares University, Children's Medical Center, Pediatrics Center of Excellence,

Significance:Likely pathogenic

Review Status:no assertion criteria provided

Collection Method:clinical testing

- -

Jan 30, 2022

Fulgent Genetics, Fulgent Genetics

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Nov 09, 2023

Baylor Genetics

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

not provided

Pathogenic:1

Nov 21, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change creates a premature translational stop signal (p.Tyr198*) in the MLC1 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in MLC1 are known to be pathogenic (PMID: 11254442, 16470554, 24824219). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This premature translational stop signal has been observed in individuals with megalencephalic leukoencephalopathy (PMID: 11254442, 11935341, 21555057). ClinVar contains an entry for this variant (Variation ID: 4720). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -

Megalencephalic leukoencephalopathy with subcortical cysts

Pathogenic:1

Jun 29, 2020

Natera, Inc.

Significance:Pathogenic

Review Status:no assertion criteria provided

Collection Method:clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

PhyloP100

6.9

Mutation Taster

=0/200

disease causing (ClinVar)

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.98

Details are displayed if max score is > 0.2

DS_DG_spliceai

0.98

Position offset: 5

DS_DL_spliceai

0.98

Position offset: 1

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

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over