Description
The homozygous p.Arg127Ter variant in TPP1 was identified by our study in one individual with Neuronal Ceroid Lipofuscinosis. The p.Arg127Ter variant in TPP has been reported in 8 individuals from Turkey, Mexico, US, German, UK, and Canada, with Neuronal Ceroid Lipofuscinosis, segregated with disease in 3 affected relatives from 1 families (PMID: 10330339, 21990111), and has been identified in 0.03196% (11/34420) of Latino chromosomes by the Genome Aggregation Database (gnomAD, http://gnomad.broadinstitute.org; dbSNP rs756564767). Although this variant has been seen in the general population, its frequency is low enough to be consistent with a recessive carrier frequency. This variant has also been reported pathogenic in ClinVar (Variation ID: 207569). This nonsense variant leads to a premature termination codon at position 127, which is predicted to lead to a truncated or absent protein. Loss of function of the TPP1 gene is an established disease mechanism in autosomal recessive Neuronal Ceroid Lipofuscinosis. The presence of this variant in combination with a reported pathogenic variant as well as a splice site variant absent from ClinVar, and in 3 individuals with Neuronal Ceroid Lipofuscinosis increases the likelihood that the p.Arg127Ter variant is pathogenic (PMID: 10330339, 21990111; Variation ID: 2643). In summary, this variant meets criteria to be classified as pathogenic for Neuronal Ceroid Lipofuscinosis in an autosomal recessive manner based on the predicted impact of the variant and multiple occurrences with pathogenic TPP1 variants in individuals with Neuronal Ceroid Lipofuscinosis. ACMG/AMP Criteria applied: PM2, PVS1, PM3, PP1 (Richards 2015).
| # | Sample | Method | Observation |
|---|
| Origin | Affected | Number tested | Tissue | Purpose | Method | Individuals | Allele frequency | Families | Co-occurrences |
|---|
| 1 | germline | yes | not provided | not provided | not provided | | not provided | not provided | not provided | not provided |
