chrX-72579205-T-C

Variant names:

• chrX-72579205-T-C
• rs1296603872
• NM_002637.4:c.*1797A>G

Variant summary

Our verdict is Likely benign. The variant received -5 ACMG points: 0P and 5B. BP4_Strong BS2_Supporting

The NM_002637.4(PHKA1):​c.*1797A>G variant causes a 3 prime UTR change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000356 in 112,421 control chromosomes in the GnomAD database, with no homozygous occurrence. There are 2 hemizygotes in GnomAD. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: 𝑓 0.000036 (0 hom., 2 hem., cov: 23)
• Consequence: PHKA1 NM_002637.4 3_prime_UTR
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: -0.628
• Publications: 0 publications found

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]

PHKA1 Gene-Disease associations (from GenCC):

• glycogen storage disease IXd

  Inheritance: XL, AR Classification: STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, Orphanet, Labcorp Genetics (formerly Invitae)

ACMG classification

Our verdict: Likely_benign. The variant received -5 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.88).
• BS2: High Hemizygotes in GnomAd4 at 2 XL,AR 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 rank	MANE	Protein	UniProt
PHKA1	NM_002637.4	c.*1797A>G		3_prime_UTR_variant	Exon 32 of 32	ENST00000373542.9	NP_002628.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
PHKA1	ENST00000373542.9	c.*1797A>G		3_prime_UTR_variant	Exon 32 of 32	1	NM_002637.4	ENSP00000362643.4
PHKA1	ENST00000339490.7	c.*1797A>G		3_prime_UTR_variant	Exon 31 of 31	1		ENSP00000342469.3
PHKA1	ENST00000541944.5	c.*1797A>G		3_prime_UTR_variant	Exon 30 of 30	1		ENSP00000441251.1
PHKA1	ENST00000373545.7	c.*1797A>G		3_prime_UTR_variant	Exon 32 of 32	5		ENSP00000362646.3

Frequencies

GnomAD3 genomes AF: 0.0000356 AC: 4 AN: 112421 Hom.: 0 Cov.: 23

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00146

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: 0.0000563

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 0

GnomAD4 genome AF: 0.0000356 AC: 4 AN: 112421 Hom.: 0 Cov.: 23 AF XY: 0.0000578 AC XY: 2 AN XY: 34573

African (AFR) AF: 0.00 AC: 0 AN: 30897

American (AMR) AF: 0.00 AC: 0 AN: 10643

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 2654

East Asian (EAS) AF: 0.00 AC: 0 AN: 3599

South Asian (SAS) AF: 0.00 AC: 0 AN: 2704

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 6168

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 239

European-Non Finnish (NFE) AF: 0.0000563 AC: 3 AN: 53320

Other (OTH) AF: 0.00 AC: 0 AN: 1510

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.0000453

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Glycogen storage disease IXd Uncertain:1

Jan 12, 2018

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.88
CADD	Benign	0.49
DANN	Benign	0.47
PhyloP100		-0.63

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

Other links and lift over

dbSNP: rs1296603872; hg19: chrX-71799055;