Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PM1PM2PP2PP3_Strong
The NM_000021.4(PSEN1):c.532T>C(p.Ser178Pro) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).
PSEN1 (HGNC:9508): (presenilin 1) Alzheimer's disease (AD) patients with an inherited form of the disease carry mutations in the presenilin proteins (PSEN1; PSEN2) or in the amyloid precursor protein (APP). These disease-linked mutations result in increased production of the longer form of amyloid-beta (main component of amyloid deposits found in AD brains). Presenilins are postulated to regulate APP processing through their effects on gamma-secretase, an enzyme that cleaves APP. Also, it is thought that the presenilins are involved in the cleavage of the Notch receptor, such that they either directly regulate gamma-secretase activity or themselves are protease enzymes. Several alternatively spliced transcript variants encoding different isoforms have been identified for this gene, the full-length nature of only some have been determined. [provided by RefSeq, Aug 2008]
Verdict is Likely_pathogenic. Variant got 9 ACMG points.
PM1
In a transmembrane_region Helical (size 22) in uniprot entity PSN1_HUMAN there are 19 pathogenic changes around while only 0 benign (100%) in NM_000021.4
PM2
Very rare variant in population databases, with high coverage;
PP2
Missense variant in the PSEN1 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 113 curated pathogenic missense variants (we use a threshold of 10). The gene has 14 curated benign missense variants. Gene score misZ: 2.1558 (below the threshold of 3.09). Trascript score misZ: 3.0986 (above the threshold of 3.09). GenCC associations: The gene is linked to acne inversa, familial, 3, dilated cardiomyopathy, Alzheimer disease 3, early-onset autosomal dominant Alzheimer disease, semantic dementia, Pick disease, familial isolated dilated cardiomyopathy, dilated cardiomyopathy 1U, behavioral variant of frontotemporal dementia.
PP3
MetaRNN computational evidence supports a deleterious effect, 0.977
Review Status: criteria provided, single submitter
Collection Method: clinical testing
This variant is not present in population databases (ExAC no frequency). This variant has been reported in individuals affected with Alzheimer's disease (PMID: 11524469). ClinVar contains an entry for this variant (Variation ID: 98048). Experimental studies have shown that this missense change reduces the secretase activity of the PSEN1 protein and abrogates production of AB42 and AB40 (PMID: 2793034). In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. This sequence change replaces serine with proline at codon 178 of the PSEN1 protein (p.Ser178Pro). The serine residue is highly conserved and there is a moderate physicochemical difference between serine and proline. -
not provided Other:1
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VIB Department of Molecular Genetics, University of Antwerp