rs137852293

chrX-18894400-G-A

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM2 PP3_Strong PP5_Moderate

The NM_000292.3(PHKA2):c.3341C>T(p.Thr1114Ile) variant causes a missense change involving the alteration of a 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 Likely pathogenic (★).

• Frequency: Genomes: not found (cov: 24)
• Consequence: PHKA2 NM_000292.3 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:2
• Conservation: PhyloP100: 9.85

Genes affected

PHKA2 (HGNC:8926): (phosphorylase kinase regulatory subunit alpha 2) 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, and the hepatic isoform is encoded by this gene. The beta subunit is the same in both the muscle and hepatic isoforms, and encoded by one gene. The gamma subunit also includes the skeletal muscle and hepatic isoforms, which are 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 9A, also known as X-linked liver glycogenosis. Alternatively spliced transcript variants have been reported, but the full-length nature of these variants has not been determined.[provided by RefSeq, Feb 2010]

PHKA2-AS1 (HGNC:44110): (PHKA2 antisense RNA 1)

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.995
• PP5: Variant X-18894400-G-A is Pathogenic according to our data. Variant chrX-18894400-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 10533.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
PHKA2	NM_000292.3	c.3341C>T	p.Thr1114Ile	missense_variant	32/33	ENST00000379942.5
PHKA2-AS1	NR_029379.1	n.721G>A		non_coding_transcript_exon_variant	3/3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
PHKA2	ENST00000379942.5	c.3341C>T	p.Thr1114Ile	missense_variant	32/33	1	NM_000292.3	P1

Frequencies

GnomAD3 genomes Cov.: 24

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 24

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, single submitter

Submissions by phenotype

Glycogen storage disease IXa1 Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Invitae

Sep 15, 2020

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. This sequence change replaces threonine with isoleucine at codon 1114 of the PHKA2 protein (p.Thr1114Ile). The threonine residue is highly conserved and there is a moderate physicochemical difference between threonine and isoleucine. This variant is not present in population databases (ExAC no frequency). This variant has been reported to segregate with X-linked liver glycogenosis in a single family (PMID: 8733133, 7959740) and has been found in an individual affected with a glycogen storage disease and hepatomegaly (Invitae). ClinVar contains an entry for this variant (Variation ID: 10533). Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. -

Glycogen storage disease IXa2 Pathogenic:1

Pathogenic, no assertion criteria provided

literature only

OMIM

May 01, 1996

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.82
BayesDel_addAF	Pathogenic	0.67	D
BayesDel_noAF	Pathogenic	0.73
Cadd	Uncertain	24
Dann	Uncertain	1.0
DEOGEN2	Pathogenic	0.80	D
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Pathogenic	0.99	D
M_CAP	Pathogenic	0.80	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.6	H
MutationTaster	Benign	1.0	A
PrimateAI	Pathogenic	0.80	T
PROVEAN	Pathogenic	-6.0	D
REVEL	Pathogenic	0.96
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.97
MutPred		0.94		Loss of disorder (P = 0.0247);
MVP		0.99
MPC		0.86
ClinPred		1.0	D
GERP RS		5.4
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.90
gMVP		0.95

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: rs137852293; hg19: chrX-18912518;