chrX-72580328-T-G

Variant names:

• chrX-72580328-T-G
• rs1028190311
• NM_002637.4:c.*674A>C

Variant summary

Our verdict is Benign. The variant received -9 ACMG points: 0P and 9B. BP4_Strong BS1_Supporting BS2

The NM_002637.4(PHKA1):​c.*674A>C variant causes a 3 prime UTR change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000985 in 111,664 control chromosomes in the GnomAD database, with no homozygous occurrence. There are 4 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 0.000099 (0 hom., 4 hem., cov: 23)
  • Exomes 𝑓: 0.0 (0 hom. 0 hem.)
  • Failed GnomAD Quality Control
• Consequence: PHKA1 NM_002637.4 3_prime_UTR
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.269
• 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: Benign. The variant received -9 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.82).
• BS1: Variant frequency is greater than expected in population eas. GnomAd4 allele frequency = 0.0000985 (11/111664) while in subpopulation EAS AF = 0.00114 (4/3505). AF 95% confidence interval is 0.000389. There are 0 homozygotes in GnomAd4. There are 4 alleles in the male GnomAd4 subpopulation. Median coverage is 23. This position passed quality control check. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting
• BS2: High Hemizygotes in GnomAd4 at 4 XL,AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
PHKA1	NM_002637.4	c.*674A>C		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.*674A>C		3_prime_UTR_variant	Exon 32 of 32	1	NM_002637.4	ENSP00000362643.4
PHKA1	ENST00000339490.7	c.*674A>C		3_prime_UTR_variant	Exon 31 of 31	1		ENSP00000342469.3
PHKA1	ENST00000541944.5	c.*674A>C		3_prime_UTR_variant	Exon 30 of 30	1		ENSP00000441251.1
PHKA1	ENST00000373545.7	c.*674A>C		3_prime_UTR_variant	Exon 32 of 32	5		ENSP00000362646.3

Frequencies

GnomAD3 genomes AF: 0.0000986 AC: 11 AN: 111610 Hom.: 0 Cov.: 23

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000948

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00114

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.000332

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000754

Gnomad OTH AF: 0.00

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 45 Hom.: 0 Cov.: 0 AF XY: 0.00 AC XY: 0 AN XY: 7

African (AFR) AC: 0 AN: 0

American (AMR) AF: 0.00 AC: 0 AN: 2

Ashkenazi Jewish (ASJ) AC: 0 AN: 0

East Asian (EAS) AC: 0 AN: 0

South Asian (SAS) AC: 0 AN: 0

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 1

Middle Eastern (MID) AC: 0 AN: 0

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 42

Other (OTH) AC: 0 AN: 0

GnomAD4 genome AF: 0.0000985 AC: 11 AN: 111664 Hom.: 0 Cov.: 23 AF XY: 0.000118 AC XY: 4 AN XY: 33830

African (AFR) AF: 0.00 AC: 0 AN: 30925

American (AMR) AF: 0.0000947 AC: 1 AN: 10562

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 2645

East Asian (EAS) AF: 0.00114 AC: 4 AN: 3505

South Asian (SAS) AF: 0.00 AC: 0 AN: 2560

European-Finnish (FIN) AF: 0.000332 AC: 2 AN: 6024

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 216

European-Non Finnish (NFE) AF: 0.0000754 AC: 4 AN: 53023

Other (OTH) AF: 0.00 AC: 0 AN: 1519

Alfa AF: 0.0000540 Hom.: 0

Bravo AF: 0.0000982

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	-0.82
CADD	Benign	1.8
DANN	Benign	0.68
PhyloP100		0.27

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: rs1028190311; hg19: chrX-71800178;