1-226890134-GTGA-G

Position:

• chr1-226890134-GTGA-G

Variant summary

Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PVS1_Moderate PM2 PP3 PP5_Moderate

The NM_000447.3(PSEN2):​c.886+2_886+4del variant causes a splice donor, splice donor region, intron change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000686 in 1,457,758 control chromosomes in the GnomAD database, with no homozygous occurrence. 1/1 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: PSEN2 NM_000447.3 splice_donor, splice_donor_region, intron
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 7.95

Genes affected

PSEN2 (HGNC:9509): (presenilin 2) Alzheimer's disease (AD) patients with an inherited form of the disease carry mutations in the presenilin proteins (PSEN1 or PSEN2) or 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 act are protease enzymes. Two alternatively spliced transcript variants encoding different isoforms of PSEN2 have been identified. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Likely_pathogenic. Variant got 7 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.07275427 fraction of the gene. Cryptic splice site detected, with MaxEntScore 8.3, offset of 1, new splice context is: atgGTgagc. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP3: Multiple lines of computational evidence support a deleterious effect 2: max_spliceai, phyloP100way_vertebrate [when was below the threshold]
• PP5: Variant 1-226890134-GTGA-G is Pathogenic according to our data. Variant chr1-226890134-GTGA-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 465218.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
PSEN2	NM_000447.3	c.886+2_886+4del		splice_donor_variant, splice_donor_region_variant, intron_variant		ENST00000366783.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
PSEN2	ENST00000366783.8	c.886+2_886+4del		splice_donor_variant, splice_donor_region_variant, intron_variant		5	NM_000447.3	P4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.86e-7 AC: 1 AN: 1457758 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 725462

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: 0.0000166

GnomAD4 genome Cov.: 33

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Alzheimer disease 4 Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Invitae

Sep 01, 2017

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. Donor and acceptor splice site variants typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in PSEN2 are known to be pathogenic (PMID: 18834536, 20375137, 24704512). This variant has not been reported in the literature in individuals with PSEN2-related disease. This variant is not present in population databases (ExAC no frequency). This sequence change affects a donor splice site in intron 9 of the PSEN2 gene. It is expected to disrupt RNA splicing and likely results in an absent or disrupted protein product. -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.97		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.95		Position offset: 0
DS_DL_spliceai		0.97		Position offset: -1

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs1553268799; hg19: chr1-227077835;