12-52897488-C-A

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2PP3

The NM_002273.4(KRT8):c.1392G>T(p.Lys464Asn) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000275 in 1,599,194 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 (★★).

Frequency

Genomes: 𝑓 0.00016 ( 0 hom., cov: 32)

Exomes 𝑓: 0.00029 ( 0 hom. )

Consequence

KRT8
NM_002273.4 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:2O:1

Conservation

PhyloP100: 2.39

Variant links:

Genes affected

KRT8 (HGNC:6446): (keratin 8) This gene is a member of the type II keratin family clustered on the long arm of chromosome 12. Type I and type II keratins heteropolymerize to form intermediate-sized filaments in the cytoplasm of epithelial cells. The product of this gene typically dimerizes with keratin 18 to form an intermediate filament in simple single-layered epithelial cells. This protein plays a role in maintaining cellular structural integrity and also functions in signal transduction and cellular differentiation. Mutations in this gene cause cryptogenic cirrhosis. Alternatively spliced transcript variants have been found for this gene. [provided by RefSeq, Jan 2012]

KRT8 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got 3 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

PP3

MetaRNN computational evidence supports a deleterious effect, 0.819

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE
KRT8	NM_002273.4 linkuse as main transcript	c.1392G>T	p.Lys464Asn	missense_variant	8/8	ENST00000692008.1
KRT8	NM_001256282.2 linkuse as main transcript	c.1476G>T	p.Lys492Asn	missense_variant	9/9
KRT8	NM_001256293.2 linkuse as main transcript	c.1392G>T	p.Lys464Asn	missense_variant	9/9
KRT8	NR_045962.2 linkuse as main transcript	n.1843G>T		non_coding_transcript_exon_variant	9/9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
KRT8	ENST00000692008.1 linkuse as main transcript	c.1392G>T	p.Lys464Asn	missense_variant	8/8		NM_002273.4	P2	P05787-1

Frequencies

GnomAD3 genomes

AF:

0.000164

AC:

AN:

152240

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000965

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:

0.0000941

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.000294

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.000114

AC:

AN:

237292

Hom.:

AF XY:

0.000139

AC XY:

AN XY:

129392

show subpopulations

Gnomad AFR exome

AF:

0.0000628

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.000167

Gnomad NFE exome

AF:

0.000209

Gnomad OTH exome

AF:

0.000166

GnomAD4 exome

AF:

0.000286

AC:

414

AN:

1446954

Hom.:

Cov.:

AF XY:

0.000264

AC XY:

190

AN XY:

720252

show subpopulations

Gnomad4 AFR exome

AF:

0.0000299

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:

0.0000761

Gnomad4 NFE exome

AF:

0.000354

Gnomad4 OTH exome

AF:

0.000266

GnomAD4 genome

AF:

0.000164

AC:

AN:

152240

Hom.:

Cov.:

AF XY:

0.000108

AC XY:

AN XY:

74384

show subpopulations

Gnomad4 AFR

AF:

0.0000965

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.0000941

Gnomad4 NFE

AF:

0.000294

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.000209

Hom.:

Bravo

AF:

0.000234

TwinsUK

AF:

0.000270

AC:

ALSPAC

AF:

0.000519

AC:

ESP6500AA

AF:

0.00

AC:

ESP6500EA

AF:

0.000251

AC:

ExAC

AF:

0.0000995

AC:

EpiCase

AF:

0.000327

EpiControl

AF:

0.000237

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2Other:1

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

not provided

Uncertain:1Other:1

Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	Jan 22, 2018	The K464N variant in the KRT8 gene has been reported previously in an individual with ulcerative colitis who also had a family history of irritable bowel disease (Owens et al., 2004). In vitro functional studies of K464N exhibited lowered efficiency during heterodimer formation, resulting in abnormal filament assembly and an increase in short fragments compared to wild type protein (Owens et al., 2004). K464N was also shown to severely affect the barrier function of a colonocyte monolayer, altering permeability, growth rate, and resistance to heat-stress (Zupancic et al., 2014). The K464N variant is observed in 25/123730 (0.02%) alleles from individuals of non-Finnish European background in large population cohorts (Lek et al., 2016). The K464N variant is a semi-conservative amino acid substitution, which may impact secondary protein structure as these residues differ in some properties. In-silico analyses, including protein predictors and evolutionary conservation, support that this variant does not alter protein structure/function. Based on the frequency of this variant in large population cohorts, we now interpret K464N as a variant of uncertain significance. -
not provided, no classification provided	literature only	Epithelial Biology; Institute of Medical Biology, Singapore	-	- -

not specified

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

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

Dec 27, 2023

Variant summary: KRT8 c.1392G>T (p.Lys464Asn) results in a non-conservative amino acid change in the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 0.00011 in 237292 control chromosomes (gnomAD). c.1392G>T has been reported in the literature in the heterozygous state in an individual affected with ulcerative colitis who had a family history of inflammatory bowel disease (Owens_2004). This report does not provide unequivocal conclusions about association of the variant with KRT8-Related Disorders. At least two publications report experimental evidence evaluating an impact on protein function (e.g. Owens_2004, Zupancic_2014). The variant exhibited a mildly reduced filament assembly efficiency compared to the WT protein and showed increased permeability in colon cell culture. However, at this time these findings do not allow convincing conclusions about the variant effect. The following publications have been ascertained in the context of this evaluation (PMID: 15090596, 24915158). One submitter has cited a clinical-significance assessment for this variant to ClinVar after 2014 and has classified the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as uncertain significance. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.99

BayesDel_addAF

Uncertain

0.032

BayesDel_noAF

Uncertain

0.090

Cadd

Pathogenic

Dann

Uncertain

1.0

DEOGEN2

Uncertain

0.56

D;D;D;.

Eigen

Pathogenic

0.75

Eigen_PC

Pathogenic

0.67

FATHMM_MKL

Uncertain

0.93

M_CAP

Pathogenic

0.57

MetaRNN

Pathogenic

0.82

D;D;D;D

MetaSVM

Pathogenic

1.1

MutationAssessor

Pathogenic

3.0

M;M;M;.

MutationTaster

Benign

1.0

D;D;D;D;D

PrimateAI

Pathogenic

0.83

PROVEAN

Benign

-2.0

N;N;N;N

REVEL

Pathogenic

0.88

Sift

Uncertain

0.0010

D;D;D;D

Sift4G

Uncertain

0.016

D;D;D;D

Polyphen

0.95

P;P;P;.

Vest4

0.88

MutPred

0.80

Loss of methylation at K464 (P = 0.0143);Loss of methylation at K464 (P = 0.0143);Loss of methylation at K464 (P = 0.0143);.;

MVP

0.98

MPC

1.4

ClinPred

0.61

GERP RS

4.8

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

Varity_R

0.59

gMVP

0.70

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over