rs137852546

Positions:

• chrX-72582562-C-A

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 10P and 1B. PVS1_Moderate PP5_Very_Strong BS2_Supporting

The NM_002637.4(PHKA1):​c.3334G>T​(p.Glu1112*) variant causes a stop gained change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000075 in 1,200,593 control chromosomes in the GnomAD database, with no homozygous occurrence. There are 4 hemizygotes in GnomAD. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★).

• Frequency:
  • Genomes: 𝑓 0.000027 (0 hom., 2 hem., cov: 23)
  • Exomes 𝑓: 0.0000055 (0 hom. 2 hem.)
• Consequence: PHKA1 NM_002637.4 stop_gained
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 7.82

Genes affected

PHKA1 (HGNC:8925): (phosphorylase kinase regulatory subunit alpha 1) 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 skeletal muscle 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 9D, also known as X-linked muscle glycogenosis. Alternatively spliced transcript variants encoding different isoforms have been identified in this gene. A pseudogene has been found on chromosome 1.[provided by RefSeq, Feb 2010]

ACMG classification

Verdict is Likely_pathogenic. Variant got 9 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most 50 bp of the penultimate exon, not predicted to undergo nonsense mediated mRNA decay. Fraction of 0.092 CDS is truncated, and there are 0 pathogenic variants in the truncated region.
• PP5: Variant X-72582562-C-A is Pathogenic according to our data. Variant chrX-72582562-C-A is described in ClinVar as [Pathogenic]. Clinvar id is 9923.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• BS2: High Hemizygotes in GnomAd4 at 2 XL geneVariant has number of hemizygotes lower than other variant known as pathogenic in the gene, so the strength is limited to Supporting.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
PHKA1	NM_002637.4	c.3334G>T	p.Glu1112*	stop_gained	31/32	ENST00000373542.9	NP_002628.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
PHKA1	ENST00000373542.9	c.3334G>T	p.Glu1112*	stop_gained	31/32	1	NM_002637.4	ENSP00000362643.4

Frequencies

GnomAD3 genomes AF: 0.0000269 AC: 3 AN: 111576 Hom.: 0 Cov.: 23 AF XY: 0.0000592 AC XY: 2 AN XY: 33772

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: 0.0000565

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.00000551 AC: 6 AN: 1089017 Hom.: 0 Cov.: 28 AF XY: 0.00000564 AC XY: 2 AN XY: 354779

Gnomad4 AFR exome AF: 0.00

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: 0.00000600

Gnomad4 OTH exome AF: 0.0000218

GnomAD4 genome AF: 0.0000269 AC: 3 AN: 111576 Hom.: 0 Cov.: 23 AF XY: 0.0000592 AC XY: 2 AN XY: 33772

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: 0.0000565

Gnomad4 OTH AF: 0.00

Bravo AF: 0.0000189

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Glycogen storage disease IXd Pathogenic:3

Pathogenic, no assertion criteria provided	literature only	OMIM	Nov 01, 1994	- -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Nov 27, 2023	This sequence change creates a premature translational stop signal (p.Glu1112*) in the PHKA1 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in PHKA1 are known to be pathogenic (PMID: 9731190, 15637709). This variant is not present in population databases (gnomAD no frequency). This premature translational stop signal has been observed in individual(s) with clinical features of PHKA1-related conditions (PMID: 7874115). ClinVar contains an entry for this variant (Variation ID: 9923). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site. For these reasons, this variant has been classified as Pathogenic. -
Pathogenic, criteria provided, single submitter	research	Duke University Health System Sequencing Clinic, Duke University Health System	Apr 20, 2023	- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.74	D
BayesDel_noAF	Pathogenic	0.57
CADD	Pathogenic	51
DANN	Uncertain	1.0
FATHMM_MKL	Uncertain	0.95	D
Vest4		0.47
GERP RS		5.1

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.96		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.96		Position offset: -3

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

Publications

LitVar

Other links and lift over

dbSNP: rs137852546; hg19: chrX-71802412;