rs386833661

Positions:

• chr1-40078621-A-G

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PM1 PM2 PP3_Strong PP5_Very_Strong

The NM_000310.4(PPT1):​c.665T>C​(p.Leu222Pro) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000372 in 1,613,842 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 13/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: PPT1 NM_000310.4 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:5
• Conservation: PhyloP100: 8.98

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 16 ACMG points.

• PM1: In a chain Palmitoyl-protein thioesterase 1 (size 278) in uniprot entity PPT1_HUMAN there are 37 pathogenic changes around while only 3 benign (93%) in NM_000310.4
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.969
• PP5: Variant 1-40078621-A-G is Pathogenic according to our data. Variant chr1-40078621-A-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 56210.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr1-40078621-A-G is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
PPT1	NM_000310.4	c.665T>C	p.Leu222Pro	missense_variant	7/9	ENST00000642050.2	NP_000301.1
PPT1	NM_001363695.2	c.665T>C	p.Leu222Pro	missense_variant	7/8		NP_001350624.1
PPT1	NM_001142604.2	c.356T>C	p.Leu119Pro	missense_variant	4/6		NP_001136076.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
PPT1	ENST00000642050.2	c.665T>C	p.Leu222Pro	missense_variant	7/9		NM_000310.4	ENSP00000493153	P1

Frequencies

GnomAD3 genomes AF: 0.0000131 AC: 2 AN: 152204 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

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: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000294

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1461638 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727134

Gnomad4 AFR exome AF: 0.00

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: 0.00

Gnomad4 NFE exome AF: 0.00000360

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.0000131 AC: 2 AN: 152204 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74366

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000294

Gnomad4 OTH AF: 0.00

Alfa AF: 0.00000961 Hom.: 0

Bravo AF: 0.00000378

ESP6500AA AF: 0.00 AC: 0

ESP6500EA AF: 0.000116 AC: 1

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Neuronal ceroid lipofuscinosis 1 Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	May 08, 2023	For these reasons, this variant has been classified as Pathogenic. Experimental studies have shown that this missense change affects PPT1 function (PMID: 28878621). 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 PPT1 protein function. ClinVar contains an entry for this variant (Variation ID: 56210). This missense change has been observed in individual(s) with clinical features of neuronal ceroid lipofuscinosis (PMID: 19302939, 23374165). This variant is present in population databases (rs386833661, gnomAD 0.007%). This sequence change replaces leucine, which is neutral and non-polar, with proline, which is neutral and non-polar, at codon 222 of the PPT1 protein (p.Leu222Pro). -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Mar 18, 2023	- -
Likely pathogenic, no assertion criteria provided	literature only	Juha Muilu Group; Institute for Molecular Medicine Finland (FIMM)	-	- -

Spastic ataxia Pathogenic:1

Likely pathogenic, criteria provided, single submitter

research

Molecular Medicine for Neurodegenerative and Neuromuscular Diseases Unit, IRCCS Fondazione Stella Maris

Jul 12, 2021

- -

Neuronal ceroid lipofuscinosis Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

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

Nov 01, 2019

Variant summary: PPT1 c.665T>C (p.Leu222Pro) 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 3.2e-05 in 31368 control chromosomes. c.665T>C has been reported in the literature in multiple individuals affected with Neuronal Ceroid-Lipofuscinosis (Batten Disease) (Mazzei_2002, Simonati_2009, Santorelli_2013). These data indicate that the variant is very likely to be associated with disease. Simonati et al report that this mutation occurs in the hydrophobic pouch of PPT-1, and the introduction of a proline may hamper the correct folding and therefore the beta-sheet conformation of the protein (Simonati_2009). No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014. Based on the evidence outlined above, the variant was classified as pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.97
BayesDel_addAF	Pathogenic	0.59	D
BayesDel_noAF	Pathogenic	0.61
CADD	Pathogenic	31
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.99	D;.;.;.;.;.;.;.
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.93
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Uncertain	0.96	.;D;T;D;D;D;D;D
M_CAP	Pathogenic	0.38	D
MetaRNN	Pathogenic	0.97	D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	4.0	H;.;.;.;.;.;.;.
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Pathogenic	0.80	T
PROVEAN	Pathogenic	-6.7	.;.;D;.;.;.;D;.
REVEL	Pathogenic	0.98
Sift	Pathogenic	0.0	.;.;D;.;.;.;D;.
Sift4G	Pathogenic	0.0010	.;.;D;.;.;.;D;.
Polyphen		1.0	D;.;.;.;.;.;D;.
Vest4		0.99, 0.96
MVP		1.0
MPC		0.74
ClinPred		1.0	D
GERP RS		5.4
Varity_R		0.99
gMVP		0.89

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

Other links and lift over

dbSNP: rs386833661; hg19: chr1-40544293;