chrX-18893592-A-G

Position:

• chrX-18893592-A-G

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM1 PP3_Strong

The NM_000292.3(PHKA2):​c.3601T>C​(p.Tyr1201His) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000638 in 1,097,556 control chromosomes in the GnomAD database, with no homozygous occurrence. There are 1 hemizygotes in GnomAD. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 24)
  • Exomes 𝑓: 0.0000064 (0 hom. 1 hem.)
• Consequence: PHKA2 NM_000292.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 8.89

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 6 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 3 uncertain in NM_000292.3
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.947

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
PHKA2	NM_000292.3	c.3601T>C	p.Tyr1201His	missense_variant	33/33	ENST00000379942.5
PHKA2-AS1	NR_029379.1	n.467+254A>G		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
PHKA2	ENST00000379942.5	c.3601T>C	p.Tyr1201His	missense_variant	33/33	1	NM_000292.3	P1
PHKA2-AS1	ENST00000452900.5	n.467+254A>G		intron_variant, non_coding_transcript_variant		1

Frequencies

GnomAD3 genomes Cov.: 24

GnomAD3 exomes AF: 0.00000546 AC: 1 AN: 182993 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 67587

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 SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000123

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000638 AC: 7 AN: 1097556 Hom.: 0 Cov.: 29 AF XY: 0.00000276 AC XY: 1 AN XY: 362922

Gnomad4 AFR exome AF: 0.0000379

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: 0.00000713

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 24

Bravo AF: 0.00000756

ESP6500AA AF: 0.00 AC: 0

ESP6500EA AF: 0.000149 AC: 1

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

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

Oct 11, 2021

Variant summary: PHKA2 c.3601T>C (p.Tyr1201His) results in a conservative amino acid change in the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 5.5e-06 in 182993 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.3601T>C has been reported in the literature as a non-informative genotype (second allele not specified) in at-least one individual affected with GSD type IX (Glycogen Phosphorylase Kinase Deficiency) (example, Brown_2015). These report(s) do not provide unequivocal conclusions about association of the variant with Glycogen Phosphorylase Kinase Deficiency. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. 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 uncertain significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.80
BayesDel_addAF	Pathogenic	0.51	D
BayesDel_noAF	Pathogenic	0.54
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.75	D
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Pathogenic	1.0	D
M_CAP	Pathogenic	0.62	D
MetaRNN	Pathogenic	0.95	D
MetaSVM	Uncertain	0.65	D
MutationAssessor	Pathogenic	3.5	H
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.74	T
PROVEAN	Pathogenic	-4.9	D
REVEL	Pathogenic	0.86
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.94
MVP		0.93
MPC		0.94
ClinPred		0.99	D
GERP RS		6.1
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.6
Varity_R		0.89
gMVP		0.87

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: rs373407231; hg19: chrX-18911710;