rs796053439
Variant summary
Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PM1PM2PM5PP3_ModeratePP5_Very_Strong
The NM_000391.4(TPP1):c.833A>G(p.Gln278Arg) variant causes a missense change. The variant allele was found at a frequency of 0.00000248 in 1,613,972 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 (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. Q278P) has been classified as Likely pathogenic.
Frequency
Consequence
NM_000391.4 missense
Scores
Clinical Significance
Conservation
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ACMG classification
Verdict is Pathogenic. Variant got 16 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes AF: 0.00000657 AC: 1AN: 152106Hom.: 0 Cov.: 31
GnomAD3 exomes AF: 0.00000398 AC: 1AN: 251460Hom.: 0 AF XY: 0.00000736 AC XY: 1AN XY: 135904
GnomAD4 exome AF: 0.00000205 AC: 3AN: 1461866Hom.: 0 Cov.: 41 AF XY: 0.00000138 AC XY: 1AN XY: 727238
GnomAD4 genome AF: 0.00000657 AC: 1AN: 152106Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0AN XY: 74304
ClinVar
Submissions by phenotype
not provided Pathogenic:2
This sequence change replaces glutamine, which is neutral and polar, with arginine, which is basic and polar, at codon 278 of the TPP1 protein (p.Gln278Arg). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This missense change has been observed in individual(s) with clinical features of neuronal ceroid lipofuscinosis (PMID: 22612257). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 207582). 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 with a positive predictive value of 95%. 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. -
p.Gln278Arg (Q278R) CAG>CGG: c.833 A>G in exon 7 of the TPP1 gene (NM_000391.3)The Q278R missense mutation in the TPP1 gene has been reported previously in two siblings with myoclonicastatic epilepsy and abnormal TPP1 enzyme analysis who had a second disease-causing mutation on the other allele (Lemke et al., 2012). Additionally, a different missense substitution at the same codon, Q278P, has been reported as a disease-causing mutation in a patient with electron microscopy findings consistent with neuronal ceroid lipofuscinosis (Ju et al., 2002). The Q278R amino acid substitution is non-conservative, which is likely to impact secondary protein structure as these residues differ in polarity, charge, size and/or other properties. Therefore, Q278R is considered to be a disease-causing mutation. The variant is found in CHILD-EPI,PME-EPI panel(s). -
Neuronal ceroid lipofuscinosis 2 Pathogenic:2
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Neuronal ceroid lipofuscinosis Pathogenic:1
Variant summary: TPP1 c.833A>G (p.Gln278Arg) results in a conservative amino acid change located in the Sedolisin domain (IPR030400) of 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 4e-06 in 251460 control chromosomes. c.833A>G has been reported in the literature in compound heterozygous individuals affected with or with clinical features of Neuronal Ceroid-Lipofuscinosis (Batten Disease) including with evidence of familial segregation and in trans with a pathogenic variant (Lemke_2012, Bowling_2017, Lindy_2018). These data indicate that the variant may be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publications have been ascertained in the context of this evaluation (PMID: 28554332, 22612257, 29655203). Three clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. All laboratories classified the variant as pathogenic (n=1) or likely pathogenic (n=2). Based on the evidence outlined above, the variant was classified as likely pathogenic. -
Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at