11-6616689-G-T

Position:

• chr11-6616689-G-T

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2 PM5 PP5_Moderate

The NM_000391.4(TPP1):​c.858C>A​(p.Asn286Lys) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. 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. N286S) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 31)
• Consequence: TPP1 NM_000391.4 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 5.19

Genes affected

TPP1 (HGNC:2073): (tripeptidyl peptidase 1) This gene encodes a member of the sedolisin family of serine proteases. The protease functions in the lysosome to cleave N-terminal tripeptides from substrates, and has weaker endopeptidase activity. It is synthesized as a catalytically-inactive enzyme which is activated and auto-proteolyzed upon acidification. Mutations in this gene result in late-infantile neuronal ceroid lipofuscinosis, which is associated with the failure to degrade specific neuropeptides and a subunit of ATP synthase in the lysosome. [provided by RefSeq, Jul 2008]

TPP1 (HGNC:):

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr11-6616690-T-C is described in Lovd as [Pathogenic].
• PP5: Variant 11-6616689-G-T is Pathogenic according to our data. Variant chr11-6616689-G-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 527750.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TPP1	NM_000391.4	c.858C>A	p.Asn286Lys	missense_variant	7/13	ENST00000299427.12	NP_000382.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TPP1	ENST00000299427.12	c.858C>A	p.Asn286Lys	missense_variant	7/13	1	NM_000391.4	ENSP00000299427.6

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 42

GnomAD4 genome Cov.: 31

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Oct 24, 2022

This sequence change replaces asparagine, which is neutral and polar, with lysine, which is basic and polar, at codon 286 of the TPP1 protein (p.Asn286Lys). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with TPP1-related conditions. ClinVar contains an entry for this variant (Variation ID: 527750). 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 expected to disrupt TPP1 protein function. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. This variant disrupts the p.Asn286 amino acid residue in TPP1. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 12376936, 14736728, 15317752, 19038966, 20340139). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.53
BayesDel_addAF	Uncertain	0.13	D
BayesDel_noAF	Uncertain	-0.060
CADD	Benign	21
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.70	D;.;.;.;.;.;.
Eigen	Benign	0.17
Eigen_PC	Benign	0.17
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Uncertain	0.92	D;.;D;.;D;.;D
M_CAP	Pathogenic	0.35	D
MetaRNN	Uncertain	0.73	D;D;D;D;D;D;D
MetaSVM	Uncertain	0.79	D
MutationAssessor	Benign	1.8	L;.;.;.;.;.;.
PrimateAI	Pathogenic	0.81	D
PROVEAN	Uncertain	-3.0	D;D;.;.;.;.;.
REVEL	Uncertain	0.60
Sift	Uncertain	0.0040	D;T;.;.;.;.;.
Sift4G	Benign	0.26	T;T;.;.;.;.;.
Polyphen		0.79	P;.;.;.;.;.;.
Vest4		0.88
MutPred		0.63		Gain of methylation at N286 (P = 0.0189);.;.;.;Gain of methylation at N286 (P = 0.0189);.;.;
MVP		0.93
MPC		0.57
ClinPred		0.96	D
GERP RS		2.7
Varity_R		0.80
gMVP		0.78

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.27		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.27		Position offset: -28

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

Publications

LitVar

Other links and lift over

dbSNP: rs1420315178; hg19: chr11-6637920;