4-99608977-G-A

Variant names:

Variant summary

Our verdict is Likely pathogenic. The variant received 8 ACMG points: 8P and 0B. PM2PM5PP3_Strong

The NM_001386140.1(MTTP):c.1769G>A(p.Ser590Asn) variant causes a missense, splice region change. The variant allele was found at a frequency of 0.00000249 in 1,608,752 control chromosomes in the GnomAD database, with no homozygous occurrence. 2/3 splice prediction tools predicting alterations to normal splicing. 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. S590I) has been classified as Pathogenic.

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000021 ( 0 hom. )

Consequence

MTTP
NM_001386140.1 missense, splice_region

Scores

Splicing: ADA: 1.000

Clinical Significance

Uncertain significance criteria provided, single submitter U:1

Conservation

PhyloP100: 7.16

Publications

14 publications found

Variant links:

Genes affected

MTTP (HGNC:7467): (microsomal triglyceride transfer protein) MTP encodes the large subunit of the heterodimeric microsomal triglyceride transfer protein. Protein disulfide isomerase (PDI) completes the heterodimeric microsomal triglyceride transfer protein, which has been shown to play a central role in lipoprotein assembly. Mutations in MTP can cause abetalipoproteinemia. [provided by RefSeq, Jul 2008]

MTTP Gene-Disease associations (from GenCC):

abetalipoproteinemia
Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Orphanet, Ambry Genetics, PanelApp Australia, G2P

MTTP links:

ENSG00000248676 (HGNC:):

ENSG00000248676 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_pathogenic. The variant received 8 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

PM5

Other missense variant is known to change same aminoacid residue: Variant chr4-99608977-G-T is described in ClinVar as Pathogenic. ClinVar VariationId is 14241.Status of the report is no_assertion_criteria_provided, 0 stars.

PP3

Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. Scorers claiming Uncertain: max_spliceai. No scorers claiming Benign.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MTTP	NM_001386140.1 link	c.1769G>A	p.Ser590Asn	missense_variant, splice_region_variant	Exon 12 of 18	ENST00000265517.10	NP_001373069.1
MTTP	NM_000253.4 link	c.1769G>A	p.Ser590Asn	missense_variant, splice_region_variant	Exon 13 of 19		NP_000244.2	P55157-1
MTTP	NM_001300785.2 link	c.1520G>A	p.Ser507Asn	missense_variant, splice_region_variant	Exon 12 of 18		NP_001287714.2	P55157B7Z7X3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MTTP	ENST00000265517.10 link	c.1769G>A	p.Ser590Asn	missense_variant, splice_region_variant	Exon 12 of 18	1	NM_001386140.1	ENSP00000265517.5		P55157-1

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152148

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:

0.00

Gnomad OTH

AF:

0.000478

GnomAD4 exome

AF:

0.00000206

AC:

AN:

1456604

Hom.:

Cov.:

AF XY:

0.00000276

AC XY:

AN XY:

724912

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33372

American (AMR)

AF:

0.0000224

AC:

AN:

44712

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26098

East Asian (EAS)

AF:

0.00

AC:

AN:

39654

South Asian (SAS)

AF:

0.00

AC:

AN:

86118

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53388

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5756

European-Non Finnish (NFE)

AF:

9.03e-7

AC:

AN:

1107286

Other (OTH)

AF:

0.0000166

AC:

AN:

60220

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.558

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

AF:

0.00000657

AC:

AN:

152148

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74332

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41420

American (AMR)

AF:

0.00

AC:

AN:

15280

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5190

South Asian (SAS)

AF:

0.00

AC:

AN:

4826

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10614

Middle Eastern (MID)

AF:

0.00

AC:

AN:

314

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68028

Other (OTH)

AF:

0.000478

AC:

AN:

2092

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.625

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.:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

not provided

Uncertain:1

Aug 07, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces serine, which is neutral and polar, with asparagine, which is neutral and polar, at codon 590 of the MTTP protein (p.Ser590Asn). This variant also falls at the last nucleotide of exon 13, which is part of the consensus splice site for this exon. This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with MTTP-related conditions. ClinVar contains an entry for this variant (Variation ID: 1350670). Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated. Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. 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. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Uncertain

0.43

BayesDel_addAF

Benign

-0.052

BayesDel_noAF

Benign

-0.31

CADD

Pathogenic

(source)

DANN

Uncertain

1.0

DEOGEN2

Benign

0.20

.;T;T

Eigen

Uncertain

0.60

Eigen_PC

Uncertain

0.58

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Uncertain

0.88

D;.;D

M_CAP

Benign

0.036

MetaRNN

Uncertain

0.66

D;D;D

MetaSVM

Benign

-0.36

MutationAssessor

Pathogenic

2.9

.;M;M

PhyloP100

7.2

PrimateAI

Uncertain

0.58

PROVEAN

Benign

-0.88

N;N;N

REVEL

Benign

0.23

Sift

Benign

0.068

T;T;T

Sift4G

Uncertain

0.024

D;D;D

Polyphen

1.0

D;D;D

Vest4

0.68

MutPred

0.42

Loss of glycosylation at P615 (P = 0.0617);.;.;

MVP

0.85

MPC

0.24

ClinPred

0.95

GERP RS

5.0

Varity_R

0.35

gMVP

0.59

Mutation Taster

=16/84

disease causing

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Pathogenic

1.0

dbscSNV1_RF

Pathogenic

1.0

SpliceAI score (max)

0.41

Details are displayed if max score is > 0.2

DS_DL_spliceai

0.41

Position offset: 0

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

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over