rs1554902052

Variant names:

• chr11-6617430-T-C
• rs1554902052
• NM_000391.4:c.381-2A>G

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000391.4(TPP1):​c.381-2A>G variant causes a splice acceptor, intron change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: TPP1 NM_000391.4 splice_acceptor, intron
• Scores: Splicing: ADA: 0.9999
• Clinical Significance: Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 6.16

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]

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, Cryptic splice site detected, with MaxEntScore 4.6, offset of -29, new splice context is: ttcttctgttccgttttgAGctt. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 11-6617430-T-C is Pathogenic according to our data. Variant chr11-6617430-T-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 495859.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
TPP1	NM_000391.4	c.381-2A>G		splice_acceptor_variant, intron_variant	Intron 4 of 12	ENST00000299427.12	NP_000382.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TPP1	ENST00000299427.12	c.381-2A>G		splice_acceptor_variant, intron_variant	Intron 4 of 12	1	NM_000391.4	ENSP00000299427.6

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 34

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:1

Jul 21, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects an acceptor splice site in intron 4 of the TPP1 gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in TPP1 are known to be pathogenic (PMID: 10330339). 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. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. ClinVar contains an entry for this variant (Variation ID: 495859). Disruption of this splice site has been observed in individual(s) with late-infantile neuronal ceroid lipofuscinosis (PMID: 11339651). This variant is not present in population databases (ExAC no frequency). -

Neuronal ceroid lipofuscinosis Pathogenic:1

May 01, 2017

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

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: The TPP1 c.381-2A>G (IVS4-2A>G) variant involves the alteration of a conserved intronic nucleotide. One in silico tool predicts a damaging outcome for this variant. 5/5 splice prediction tools predict significant impact on normal splicing-loss of canonical splicing acceptor site. ESEfinder predicts changes of binding motifs for splicing enhancers. Consistently, Xiong_2015 used computational modeling and predicted variant to induce large splicing changes. However, these predictions have yet to be confirmed by functional studies. This variant is absent in 121164 control chromosomes. The variant of interest has reported in an affected individual with LINCL as compound heterozygote. Taken together, due to lack of clinical and functional evidence, this variant is classified as likely pathogenic. -

Neuronal ceroid lipofuscinosis 2 Pathogenic:1

Nov 17, 2017

Counsyl

Significance: Likely pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Uncertain	0.020
CADD	Pathogenic	34
DANN	Uncertain	0.99
Eigen	Pathogenic	0.97
Eigen_PC	Pathogenic	0.79
FATHMM_MKL	Uncertain	0.91	D
GERP RS		5.0

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.93
SpliceAI score (max)		0.95		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.64		Position offset: -10
DS_AL_spliceai		0.95		Position offset: -2

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

Publications

LitVar

Other links and lift over

dbSNP: rs1554902052; hg19: chr11-6638661;