chrX-18893579-G-A

Position:

• chrX-18893579-G-A

Variant summary

Our verdict is Pathogenic. Variant got 14 ACMG points: 14P and 0B. PM2 PP3_Strong PP5_Very_Strong

The NM_000292.3(PHKA2):​c.3614C>T​(p.Pro1205Leu) 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 Pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. P1205P) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 23)
• Consequence: PHKA2 NM_000292.3 missense
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:9
• Conservation: PhyloP100: 9.54

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 Pathogenic. Variant got 14 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.993
• PP5: Variant X-18893579-G-A is Pathogenic according to our data. Variant chrX-18893579-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 10531.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chrX-18893579-G-A is described in Lovd as [Pathogenic]. Variant chrX-18893579-G-A is described in Lovd as [Pathogenic]. Variant chrX-18893579-G-A is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
PHKA2	NM_000292.3	c.3614C>T	p.Pro1205Leu	missense_variant	33/33	ENST00000379942.5
PHKA2-AS1	NR_029379.1	n.467+241G>A		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
PHKA2	ENST00000379942.5	c.3614C>T	p.Pro1205Leu	missense_variant	33/33	1	NM_000292.3	P1
PHKA2-AS1	ENST00000452900.5	n.467+241G>A		intron_variant, non_coding_transcript_variant		1

Frequencies

GnomAD3 genomes Cov.: 23

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 23

Bravo AF: 0.00000378

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:9

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Glycogen storage disease IXa1 Pathogenic:5

Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Oct 05, 2022	ClinVar contains an entry for this variant (Variation ID: 10531). For these reasons, this variant has been classified as Pathogenic. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on PHKA2 protein function. This missense change has been observed in individuals with glycogen storage disease or phosphorylase kinase (PHK) deficiency (PMID: 7847371, 9870210, 21646031, 21911307, 24055370, 25266922, 28468868). It has also been observed to segregate with disease in related individuals. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces proline, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 1205 of the PHKA2 protein (p.Pro1205Leu). -
Pathogenic, no assertion criteria provided	literature only	OMIM	Feb 01, 1995	- -
Pathogenic, criteria provided, single submitter	clinical testing	Foundation for Research in Genetics and Endocrinology, FRIGE's Institute of Human Genetics	Jul 03, 2021	A hemizygous missense variation in exon 33 of the PHKA2 gene that results in the amino acid substitution of Leucine for Proline at codon 1205 was detected. The observed variant c.3614C>T (p.Pro1205Leu) has not been reported in the 1000 genomes and gnomAD databases. The observed variant has previously been reported in multiple unrelated patients affected with glycogen storage disorders (Davit-Spraul et al 2011). The in silico prediction of the variant are probably damaging by PolyPhen-2 (HumDiv) and damaging by SIFT, LRT and MutationTaster2. The reference codon is conserved across species. In summary, the variant meets our criteria to be classified as pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Jun 27, 2018	Variant summary: PHKA2 c.3614C>T (p.Pro1205Leu) results in a non-conservative amino acid change in the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 200197 control chromosomes (gnomAD). The variant, c.3614C>T, has been reported in the literature in multiple individuals both in heterozygote females and hemizygote males affected with Glycogen storage disease, type IXa1. Cho_2013 reports the variant in a female Chinese patient accompanied with a skewed X-chromosome inactivation, therefore, explaining the phenotypic representation in some females. Achouitar_2011 suggests the variant to be a Dutch founder mutation. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014. Based on the evidence outlined above, the variant was classified as pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Apr 03, 2020	- -

not provided Pathogenic:4

Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Sep 14, 2023	Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 34946936, 34134972, 35854365, 2303074, 25266922, 7847371, 22899091, 33834518, 31508908, 31248825, 10330341, Estrada2020[CaseReport], 30659246, 24055370, 21646031, 28468868, 9870210, 33763395, 34440436, 21911307) -
Pathogenic, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	May 01, 2019	- -
Pathogenic, no assertion criteria provided	clinical testing	Joint Genome Diagnostic Labs from Nijmegen and Maastricht, Radboudumc and MUMC+	-	- -
Pathogenic, no assertion criteria provided	clinical testing	Genome Diagnostics Laboratory, University Medical Center Utrecht	-	- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.92
BayesDel_addAF	Pathogenic	0.67	D
BayesDel_noAF	Pathogenic	0.73
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.66	D
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Pathogenic	1.0	D
M_CAP	Pathogenic	0.83	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.1	M
MutationTaster	Benign	1.0	A
PrimateAI	Uncertain	0.74	T
PROVEAN	Pathogenic	-9.8	D
REVEL	Pathogenic	0.92
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.78
MutPred		0.92		Loss of disorder (P = 0.0518);
MVP		1.0
MPC		0.55
ClinPred		1.0	D
GERP RS		5.9
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.6
Varity_R		0.92
gMVP		0.78

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: rs137852288; hg19: chrX-18911697; COSMIC: COSV66053208; COSMIC: COSV66053208;