rs386833649

chr1-40089456-G-A

Variant summary

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

The NM_000310.4(PPT1):c.490C>T(p.Arg164Ter) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000821 in 1,461,874 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 Likely pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. R164R) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 0.0000082 (0 hom.)
• Consequence: PPT1 NM_000310.4 stop_gained
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:6
• Conservation: PhyloP100: 2.92

Genes affected

PPT1 (HGNC:9325): (palmitoyl-protein thioesterase 1) The protein encoded by this gene is a small glycoprotein involved in the catabolism of lipid-modified proteins during lysosomal degradation. The encoded enzyme removes thioester-linked fatty acyl groups such as palmitate from cysteine residues. Defects in this gene are a cause of infantile neuronal ceroid lipofuscinosis 1 (CLN1, or INCL) and neuronal ceroid lipofuscinosis 4 (CLN4). Two transcript variants encoding different isoforms have been found for this gene.[provided by RefSeq, Dec 2008]

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 1-40089456-G-A is Pathogenic according to our data. Variant chr1-40089456-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 56197.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr1-40089456-G-A is described in Lovd as [Pathogenic]. Variant chr1-40089456-G-A is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
PPT1	NM_000310.4	c.490C>T	p.Arg164Ter	stop_gained	5/9	ENST00000642050.2
PPT1	NM_001363695.2	c.490C>T	p.Arg164Ter	stop_gained	5/8
PPT1	NM_001142604.2	c.181C>T	p.Arg61Ter	stop_gained	2/6

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
PPT1	ENST00000642050.2	c.490C>T	p.Arg164Ter	stop_gained	5/9		NM_000310.4	P1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD3 exomes AF: 0.00000795 AC: 2 AN: 251428 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135880

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000544

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000879

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000821 AC: 12 AN: 1461874 Hom.: 0 Cov.: 32 AF XY: 0.00000688 AC XY: 5 AN XY: 727242

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.000126

Gnomad4 SAS exome AF: 0.0000116

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000540

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 31

Alfa AF: 0.0000442 Hom.: 0

Bravo AF: 0.00000756

ExAC AF: 0.0000165 AC: 2

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:6

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Neuronal ceroid lipofuscinosis 1 Pathogenic:6

Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Oct 05, 2023	- -
Pathogenic, criteria provided, single submitter	curation	Broad Center for Mendelian Genomics, Broad Institute of MIT and Harvard	Jan 25, 2023	The homozygous p.Arg164Ter variant in PPT1 was identified by our study in two siblings with neuronal ceroid lipofuscinosis. The p.Arg164Ter variant in PPT1 has been previously reported in four unrelated individuals with neuronal ceroid lipofuscinosis 1 (PMID: 31741823, PMID: 21990111, PMID: 10649502, PMID: 9664077), but has been identified in 0.005% (1/18394) of East Asian chromosomes by the Genome Aggregation Database (gnomAD, http://gnomad.broadinstitute.org; dbSNP ID: rs386833649). Although this variant has been seen in the general population in a heterozygous state, its frequency is low enough to be consistent with a recessive carrier frequency. Of the four affected individuals previously reported (PMID: 31741823, PMID: 21990111, PMID: 10649502, PMID: 9664077), three were compound heterozygotes who carried pathogenic or likely pathogenic variants in trans (PMID: 31741823, PMID: 21990111, PMID: 9664077, ClinVar Variation ID: 8904), and one was a compound heterozygote who carried a variant of uncertain significance in trans (PMID: 10649502, ClinVar Variation ID: 56217), and the affected siblings identified by our study were homozygotes, which increases the likelihood that the p.Arg164Ter variant is pathogenic. This variant has also been reported in ClinVar (Variation ID: 56197) and has been interpreted as pathogenic by Invitae and the Shahid Beheshti University of Medical Sciences Genomic Research Center and as likely pathogenic by Counsyl. This nonsense variant leads to a premature termination codon at position 164, which is predicted to lead to a truncated or absent protein. Loss of function of the PPT1 gene is an established mechanism of autosomal recessive neuronal ceroid lipofuscinosis 1. In summary, this variant meets criteria to be classified as pathogenic for autosomal recessive neuronal ceroid lipofuscinosis 1. ACMG/AMP Criteria applied: PVS1, PM2_Supporting, PM3_Strong (Richards 2015). -
Likely pathogenic, no assertion criteria provided	literature only	Juha Muilu Group; Institute for Molecular Medicine Finland (FIMM)	-	- -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Jan 08, 2024	This sequence change creates a premature translational stop signal (p.Arg164*) in the PPT1 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in PPT1 are known to be pathogenic (PMID: 10679943, 21990111). This variant is present in population databases (rs386833649, gnomAD 0.006%). This premature translational stop signal has been observed in individuals with neuronal ceroid lipofuscinosis (PMID: 9664077, 10649502). ClinVar contains an entry for this variant (Variation ID: 56197). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -
Likely pathogenic, criteria provided, single submitter	literature only	Counsyl	Aug 26, 2014	- -
Pathogenic, criteria provided, single submitter	clinical testing	Genomic Research Center, Shahid Beheshti University of Medical Sciences	Dec 18, 2017	- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.51	D
BayesDel_noAF	Pathogenic	0.58
Cadd	Pathogenic	37
Dann	Uncertain	1.0
Eigen	Uncertain	0.38
Eigen_PC	Benign	0.20
FATHMM_MKL	Uncertain	0.95	D
MutationTaster	Benign	1.0	A;A
Vest4		0.84
GERP RS		2.4
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.15		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

Other links and lift over

dbSNP: rs386833649; hg19: chr1-40555128;