chr1-40080483-C-T
Variant summary
Our verdict is Pathogenic. The variant received 16 ACMG points: 16P and 0B. PM1PM2PM5PP3_ModeratePP5_Very_Strong
The NM_000310.4(PPT1):c.541G>A(p.Val181Met) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000576 in 1,613,306 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 Pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. V181L) has been classified as Likely pathogenic.
Frequency
Consequence
NM_000310.4 missense
Scores
Clinical Significance
Conservation
Publications
- neuronal ceroid lipofuscinosisInheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
- neuronal ceroid lipofuscinosis 1Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, Labcorp Genetics (formerly Invitae), ClinGen, G2P, Orphanet, Myriad Women’s Health
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ACMG classification
Our verdict: Pathogenic. The variant received 16 ACMG points.
Transcripts
RefSeq
| Gene | Transcript | HGVSc | HGVSp | Effect | Exon rank | MANE | Protein | UniProt |
|---|---|---|---|---|---|---|---|---|
| PPT1 | NM_000310.4 | c.541G>A | p.Val181Met | missense_variant | Exon 6 of 9 | ENST00000642050.2 | NP_000301.1 | |
| PPT1 | NM_001363695.2 | c.541G>A | p.Val181Met | missense_variant | Exon 6 of 8 | NP_001350624.1 | ||
| PPT1 | NM_001142604.2 | c.232G>A | p.Val78Met | missense_variant | Exon 3 of 6 | NP_001136076.1 |
Ensembl
Frequencies
GnomAD3 genomes AF: 0.0000132 AC: 2AN: 151758Hom.: 0 Cov.: 32 show subpopulations
GnomAD2 exomes AF: 0.0000875 AC: 22AN: 251372 AF XY: 0.0000662 show subpopulations
GnomAD4 exome AF: 0.0000623 AC: 91AN: 1461548Hom.: 0 Cov.: 32 AF XY: 0.0000550 AC XY: 40AN XY: 727112 show subpopulations
Age Distribution
GnomAD4 genome AF: 0.0000132 AC: 2AN: 151758Hom.: 0 Cov.: 32 AF XY: 0.0000270 AC XY: 2AN XY: 74072 show subpopulations
Age Distribution
ClinVar
Submissions by phenotype
Neuronal ceroid lipofuscinosis 1 Pathogenic:9
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Variant summary: PPT1 c.541G>A (p.Val181Met) results in a conservative amino acid change in the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 8.7e-05 in 277014 control chromosomes (gnomAD). This frequency is not significantly higher than expected for a pathogenic variant in PPT1 causing Neuronal Ceroid-Lipofuscinosis (Batten Disease) (8.7e-05 vs 0.00073), allowing no conclusion about variant significance. c.541G>A has been reported in the literature in multiple homozygous and compound heterozygous individuals affected with Neuronal Ceroid-Lipofuscinosis (Batten Disease, Das_1998, Santorelli_2013, Poyato_2012). These data indicate that the variant is very likely to be associated with disease. At least one publication reports experimental evidence evaluating an impact on protein enzyme activity. The most pronounced variant effect results in <10% of normal activity (Das_1998, Poyato_2012). 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. -
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This sequence change replaces valine, which is neutral and non-polar, with methionine, which is neutral and non-polar, at codon 181 of the PPT1 protein (p.Val181Met). This variant is present in population databases (rs148412181, gnomAD 0.02%). This missense change has been observed in individuals with neuronal ceroid lipofucinosis (NCL) (PMID: 9664077, 10191107, 10649502, 15464427, 19302939, 22387303, 23374165, 30541466). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 188857). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is expected to disrupt PPT1 protein function with a positive predictive value of 95%. Experimental studies have shown that this missense change affects PPT1 function (PMID: 9664077, 11440996, 28878621). This variant disrupts the p.Val181 amino acid residue in PPT1. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 19302939, 21499717). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic. -
This submission and the accompanying classification are no longer maintained by the submitter. For more information on current observations and classification, please contact variantquestions@myriad.com. -
Inborn genetic diseases Pathogenic:1
The p.V181M pathogenic mutation (also known as c.541G>A), located in coding exon 6 of the PPT1 gene, results from a G to A substitution at nucleotide position 541. The valine at codon 181 is replaced by methionine, an amino acid with highly similar properties. This mutation has been identified in multiple individuals with neuronal ceroid lipofuscinosis, including in the homozygous state in 3 individuals from 2 families (Das AK et al. J. Clin. Invest., 1998 Jul;102:361-70; Waliany S et al. Hum. Mutat., 2000 Feb;15:206-7; Mole SE et al. Hum. Mutat., 1999;14:199-215; Teixeira C et al. J. Neurol., 2003 Jun;250:661-7; Pérez Poyato MS et al. Gene, 2012 May;499:297-302; Santorelli FM et al. Orphanet J Rare Dis, 2013 Feb;8:19; Sheth J et al. BMC Neurol, 2018 Dec;18:203). Analysis of this mutation in SF9 cells as well as patient derived lymphoblasts showed o detectable palmitoyl-protein thioesterase activity (Das AK et al. Hum. Mol. Genet., 2001 Jun;10:1431-9). Another study suggested abnormal processing of protein containing this mutation (Pezzini F et al. Front Mol Neurosci, 2017 Aug;10:266). Based on the supporting evidence, this alteration is interpreted as a disease-causing mutation. -
not provided Pathogenic:1
Published functional studies demonstrate that V181M results in almost complete loss of wild-type function (Das et al., 2001); Located in the palmitate-binding site and it is hypothesized that the V181M substitution alters the active site pocket (Ohno et al., 2010); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 15464427, 12796825, 12125808, 28878621, 11073228, 11589007, 21990111, 21499717, 24091420, 15965709, 10649502, 31589614, 30541466, 33726816, 23374165, 33849402, 22387303, 11440996, 19793631, 9664077) -
Retinitis pigmentosa Pathogenic:1
The p.Val181Met variant in PPT1 was identified in an individual with Retinitis pigmentosa, via a collaborative study between the Broad Institute's Center for Mendelian Genomics and the Pierce lab (https://oculargenomics.meei.harvard.edu/labs/pierce-lab/lab-members/). Through a review of available evidence we were able to apply the following criteria: PM2, PP3, PM3, PS3, PP1-M, PM1. Based on this evidence we have classified this variant as Pathogenic. If you have any questions about the classification please reach out to the Pierce Lab. -
Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at