NM_005557.4:c.362T>C

Variant names:

• chr17-41612327-A-G
• rs28928894
• NM_005557.4:c.362T>C

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PM1 PM2 PM5 PP3_Strong PP5_Very_Strong

The NM_005557.4(KRT16):​c.362T>C​(p.Met121Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. M121K) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: KRT16 NM_005557.4 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3 O:1
• Conservation: PhyloP100: 9.20
• Publications: 8 publications found

Genes affected

KRT16 (HGNC:6423): (keratin 16) The protein encoded by this gene is a member of the keratin gene family. The keratins are intermediate filament proteins responsible for the structural integrity of epithelial cells and are subdivided into cytokeratins and hair keratins. Most of the type I cytokeratins consist of acidic proteins which are arranged in pairs of heterotypic keratin chains and are clustered in a region of chromosome 17q12-q21. This keratin has been coexpressed with keratin 14 in a number of epithelial tissues, including esophagus, tongue, and hair follicles. Mutations in this gene are associated with type 1 pachyonychia congenita, non-epidermolytic palmoplantar keratoderma and unilateral palmoplantar verrucous nevus. [provided by RefSeq, Jul 2008]

KRT16 Gene-Disease associations (from GenCC):

• pachyonychia congenita 1

  Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, Genomics England PanelApp
• palmoplantar keratoderma, nonepidermolytic, focal 1

  Inheritance: AD Classification: STRONG, MODERATE Submitted by: Ambry Genetics, Genomics England PanelApp
• isolated focal non-epidermolytic palmoplantar keratoderma

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• pachyonychia congenita

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 18 ACMG points.

• PM1: In a hotspot region, there are 14 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 2 uncertain in NM_005557.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr17-41612327-A-C is described in ClinVar as Pathogenic. ClinVar VariationId is 419351.Status of the report is criteria_provided_single_submitter, 1 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.991
• PP5: Variant 17-41612327-A-G is Pathogenic according to our data. Variant chr17-41612327-A-G is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 14608.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_005557.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	KRT16	NM_005557.4	MANE Select	c.362T>C	p.Met121Thr	missense	Exon 1 of 8	NP_005548.2

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	KRT16	ENST00000301653.9	TSL:1 MANE Select	c.362T>C	p.Met121Thr	missense	Exon 1 of 8	ENSP00000301653.3
	KRT16	ENST00000588319.1	TSL:6	n.439T>C		non_coding_transcript_exon	Exon 1 of 1
	KRT16	ENST00000593067.1	TSL:3	c.-312-41T>C		intron	N/A	ENSP00000467124.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:1 Other:1

Mar 23, 2016

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The M121T variant has been reported previously in association with pachyonychia congenita (PC) (Terrinoni et al., 2001; Wilson et al., 2014). It was not observed in approximately 6,500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, indicating it is not a common benign variant in these populations. M121T is a non-conservative amino acid substitution, which is likely to impact secondary protein structure as these residues differ in polarity, charge, size and/or other properties. This substitution occurs within a known mutational hotspot region (helix initiation motif) that is highly conserved across all species and among all members of the keratin family. Many other pathogenic variants in patients with pachyonychia congenita have been reported at the same residue (M121K) and in nearby residues (Q122P, L124H/P/R, N125D/S) according to the Human Gene Mutation Database (Stenson et al., 2014). It is well established that keratin gene mutations affecting the residues at the ends of the central rod domains of the keratin proteins (helix initiation and termination motifs) interfere with proper keratin intermediate filament assembly and function, resulting in hyperkeratosis (Chamcheu et al., 2011). Therefore, we consider M121T to be pathogenic.

Epithelial Biology; Institute of Medical Biology, Singapore

Significance: not provided

Review Status: no classification provided

Collection Method: literature only

Pachyonychia congenita 1;C4552049:Palmoplantar keratoderma, nonepidermolytic, focal 1 Pathogenic:1

Jul 03, 2021

Fulgent Genetics, Fulgent Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Pachyonychia congenita 1 Pathogenic:1

Dec 01, 2001

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.49	D
BayesDel_noAF	Pathogenic	0.46
CADD	Pathogenic	28
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.81	D
Eigen	Pathogenic	0.90
Eigen_PC	Pathogenic	0.79
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Benign	0.74	T
M_CAP	Pathogenic	0.31	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	4.3	H
PhyloP100		9.2
PrimateAI	Uncertain	0.71	T
PROVEAN	Pathogenic	-5.6	D
REVEL	Pathogenic	0.97
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.98
MutPred		0.97		Gain of glycosylation at M121 (P = 0.0435)
MVP		0.95
MPC		1.1
ClinPred		1.0	D
GERP RS		4.4
PromoterAI		0.030	Neutral
Varity_R		0.98
gMVP		0.99
Mutation Taster		=2/98	disease causing (ClinVar)

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: rs28928894; hg19: chr17-39768579;