21-25881337-AAT-A

Position:

• chr21-25881337-AAT-A

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

The NM_000484.4(APP):​c.*331_*332delAT variant causes a 3 prime UTR change. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (no stars).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: APP NM_000484.4 3_prime_UTR
• Clinical Significance: Uncertain significance no assertion criteria provided U:1
• Conservation: PhyloP100: 6.12

Genes affected

APP (HGNC:620): (amyloid beta precursor protein) This gene encodes a cell surface receptor and transmembrane precursor protein that is cleaved by secretases to form a number of peptides. Some of these peptides are secreted and can bind to the acetyltransferase complex APBB1/TIP60 to promote transcriptional activation, while others form the protein basis of the amyloid plaques found in the brains of patients with Alzheimer disease. In addition, two of the peptides are antimicrobial peptides, having been shown to have bacteriocidal and antifungal activities. Mutations in this gene have been implicated in autosomal dominant Alzheimer disease and cerebroarterial amyloidosis (cerebral amyloid angiopathy). Multiple transcript variants encoding several different isoforms have been found for this gene. [provided by RefSeq, Aug 2014]

APP (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
APP	NM_000484.4	c.*331_*332delAT		3_prime_UTR_variant	18/18	ENST00000346798.8	NP_000475.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
APP	ENST00000346798	c.*331_*332delAT		3_prime_UTR_variant	18/18	1	NM_000484.4	ENSP00000284981.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 222618 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 119266

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: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: no assertion criteria provided

Submissions by phenotype

APP-related disorder Uncertain:1

Uncertain significance, no assertion criteria provided

clinical testing

PreventionGenetics, part of Exact Sciences

Mar 17, 2024

The APP c.*331_*332delAT variant is located in the 3' untranslated region. This variant has been reported in an individual with cerebral amyloid angiopathy (Nicolas et al. 2016. PubMed ID: 25828868). In vitro functional studies using patient mRNA in HeLa cells consistently demonstrated a significant increase in APP expression (Table 3 and Figure 2, Nicolas et al. 2016. PubMed ID: 25828868). This variant has not been reported in a large population database, indicating this variant is rare; however, the quality of this data is questionable and should be interpreted with caution. Although we suspect that this variant may be pathogenic, at this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -

Computational scores

Source: dbNSFP v4.3

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: rs2036971081; hg19: chr21-27253648;