chr16-47502989-A-G

Position:

chr16-47502989-A-G

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1PM2PP5_Very_Strong

The NM_000293.3(PHKB):c.306-2A>G variant causes a splice acceptor change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000374 in 1,602,790 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: 𝑓 0.0000066 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000034 ( 0 hom. )

Consequence

PHKB
NM_000293.3 splice_acceptor

Scores

Splicing: ADA: 1.000

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3

Conservation

PhyloP100: 9.23

Variant links:

Genes affected

PHKB (HGNC:8927): (phosphorylase kinase regulatory subunit beta) Phosphorylase kinase is a polymer of 16 subunits, four each of alpha, beta, gamma and delta. The alpha subunit includes the skeletal muscle and hepatic isoforms, encoded by two different genes. The beta subunit is the same in both the muscle and hepatic isoforms, encoded by this gene, which is a member of the phosphorylase b kinase regulatory subunit family. The gamma subunit also includes the skeletal muscle and hepatic isoforms, encoded by two different genes. The delta subunit is a calmodulin and can be encoded by three different genes. The gamma subunits contain the active site of the enzyme, whereas the alpha and beta subunits have regulatory functions controlled by phosphorylation. The delta subunit mediates the dependence of the enzyme on calcium concentration. Mutations in this gene cause glycogen storage disease type 9B, also known as phosphorylase kinase deficiency of liver and muscle. Alternatively spliced transcript variants encoding different isoforms have been identified in this gene. Two pseudogenes have been found on chromosomes 14 and 20, respectively.[provided by RefSeq, Feb 2010]

PHKB links:

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ACMG classification

Classification made for transcript

Verdict is Pathogenic. Variant got 18 ACMG points.

PVS1

Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, Cryptic splice site detected, with MaxEntScore 4.3, offset of -26, new splice context is: tcaaatgcatttccaattAGttt. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in frameshift change.

PM2

Very rare variant in population databases, with high coverage;

PP5

Variant 16-47502989-A-G is Pathogenic according to our data. Variant chr16-47502989-A-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 13619.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	Effect	MANE	Protein
PHKB	NM_000293.3 linkuse as main transcript	c.306-2A>G	splice_acceptor_variant	ENST00000323584.10	NP_000284.1
PHKB	NM_001031835.3 linkuse as main transcript	c.285-2A>G	splice_acceptor_variant		NP_001027005.1
PHKB	NM_001363837.1 linkuse as main transcript	c.306-2A>G	splice_acceptor_variant		NP_001350766.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
PHKB	ENST00000323584.10 linkuse as main transcript	c.306-2A>G		splice_acceptor_variant		1	NM_000293.3	ENSP00000313504		Q93100-1

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152204

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000119

AC:

AN:

251128

Hom.:

AF XY:

0.00

AC XY:

AN XY:

135736

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000579

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00000880

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000345

AC:

AN:

1450586

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

722518

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.0000895

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:

9.08e-7

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

AF:

0.00000657

AC:

AN:

152204

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

74366

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000147

Gnomad4 OTH

AF:

0.00

Bravo

AF:

0.00000378

EpiCase

AF:

0.00

EpiControl

AF:

0.0000593

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Glycogen storage disease IXb

Pathogenic:2

Pathogenic, no assertion criteria provided	literature only	OMIM	Dec 01, 1997	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Dec 02, 2023	This sequence change affects an acceptor splice site in intron 3 of the PHKB gene. RNA analysis indicates that disruption of this splice site induces altered splicing and may result in an absent or disrupted protein product. This variant is present in population databases (rs797044442, gnomAD 0.006%). Disruption of this splice site has been observed in individual(s) with glycogen storage disease (PMID: 9402963). This variant is also known as IVS4 [‚Äì2A>G]. ClinVar contains an entry for this variant (Variation ID: 13619). Studies have shown that disruption of this splice site results in skipping of exon 4 and introduces a premature termination codon (PMID: 9402963). The resulting mRNA is expected to undergo nonsense-mediated decay. 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. -

Glycogen phosphorylase kinase deficiency

Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Oct 12, 2023

Variant summary: PHKB c.306-2A>G is located in a canonical splice-site and is predicted to affect mRNA splicing resulting in a significantly altered protein due to either exon skipping, shortening, or inclusion of intronic material. Several computational tools predict a significant impact on normal splicing: Three predict the variant abolishes a 3 acceptor site. However, these predictions have yet to be confirmed by functional studies. The variant allele was found at a frequency of 1.2e-05 in 251128 control chromosomes (gnomAD). c.306-2A>G has been reported in the literature in one individual affected with Glycogen Phosphorylase Kinase Deficiency (Burwinkel_1997). These data indicate that the variant is very likely to be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publications have been ascertained in the context of this evaluation (PMID: 17689125, 33858366, 9402963). No submitters have cited clinical-significance assessments for this variant to ClinVar after 2014. Based on the evidence outlined above, the variant was classified as pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.50

BayesDel_noAF

Pathogenic

0.31

CADD

Pathogenic

DANN

Uncertain

0.99

Eigen

Pathogenic

1.2

Eigen_PC

Pathogenic

1.0

FATHMM_MKL

Pathogenic

0.99

MutationTaster

Benign

1.0

D;D;D;D

GERP RS

5.5

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Pathogenic

1.0

dbscSNV1_RF

Pathogenic

0.94

SpliceAI score (max)

0.83

Details are displayed if max score is > 0.2

DS_AL_spliceai

0.83

Position offset: 2

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

Publications

LitVar

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over