rs780977054

Variant names:

• chr17-47944614-A-G
• rs780977054
• NM_018129.4:c.264-2A>G

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_018129.4(PNPO):​c.264-2A>G variant causes a splice acceptor, intron change. The variant allele was found at a frequency of 0.00000891 in 1,459,046 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 0.0000089 (0 hom.)
• Consequence: PNPO NM_018129.4 splice_acceptor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 7.16
• Publications: 0 publications found

Genes affected

PNPO (HGNC:30260): (pyridoxamine 5'-phosphate oxidase) The enzyme encoded by this gene catalyzes the terminal, rate-limiting step in the synthesis of pyridoxal 5'-phosphate, also known as vitamin B6. Vitamin B6 is a required co-factor for enzymes involved in both homocysteine metabolism and synthesis of neurotransmitters such as catecholamine. Mutations in this gene result in pyridoxamine 5'-phosphate oxidase (PNPO) deficiency, a form of neonatal epileptic encephalopathy. [provided by RefSeq, Oct 2008]

PNPO Gene-Disease associations (from GenCC):

• pyridoxal phosphate-responsive seizures

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, ClinGen, Labcorp Genetics (formerly Invitae), Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 18 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 17-47944614-A-G is Pathogenic according to our data. Variant chr17-47944614-A-G is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 409830.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
PNPO	NM_018129.4	c.264-2A>G		splice_acceptor_variant, intron_variant	Intron 2 of 6	ENST00000642017.2	NP_060599.1
PNPO	NM_001436305.1	c.264-2A>G		splice_acceptor_variant, intron_variant	Intron 2 of 5		NP_001423234.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
PNPO	ENST00000642017.2	c.264-2A>G		splice_acceptor_variant, intron_variant	Intron 2 of 6		NM_018129.4	ENSP00000493302.2

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD2 exomes AF: 0.00000398 AC: 1 AN: 251490 AF XY: 0.00

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.000163

GnomAD4 exome AF: 0.00000891 AC: 13 AN: 1459046 Hom.: 0 Cov.: 30 AF XY: 0.00000826 AC XY: 6 AN XY: 726008

African (AFR) AF: 0.00 AC: 0 AN: 33432

American (AMR) AF: 0.00 AC: 0 AN: 44718

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26108

East Asian (EAS) AF: 0.00 AC: 0 AN: 39684

South Asian (SAS) AF: 0.00 AC: 0 AN: 86190

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53414

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5676

European-Non Finnish (NFE) AF: 0.0000108 AC: 12 AN: 1109532

Other (OTH) AF: 0.0000166 AC: 1 AN: 60292

GnomAD4 genome Cov.: 31

Alfa AF: 0.00 Hom.: 0

TwinsUK AF: 0.00 AC: 0

ALSPAC AF: 0.000259 AC: 1

EpiCase AF: 0.00

EpiControl AF: 0.0000593

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:1

Jul 03, 2019

Athena Diagnostics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The variant disrupts a canonical splice site, and is therefore predicted to result in the loss of a functional protein. The best available variant frequency is uninformative because there are too few occurrences in population data. -

Pyridoxal phosphate-responsive seizures Pathogenic:1

Mar 26, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects an acceptor splice site in intron 2 of the PNPO gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in PNPO are known to be pathogenic (PMID: 15772097, 24645144). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with PNPO-related conditions. ClinVar contains an entry for this variant (Variation ID: 409830). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.31
CADD	Pathogenic	34
DANN	Uncertain	1.0
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.85
FATHMM_MKL	Pathogenic	0.97	D
PhyloP100		7.2
GERP RS		5.2
Mutation Taster		=0/100	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.93
SpliceAI score (max)		1.0		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.56		Position offset: 4
DS_AL_spliceai		1.0		Position offset: 2

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

Other links and lift over

dbSNP: rs780977054; hg19: chr17-46021980;