17-42900903-T-A

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 4P and 1B. PM1 PM2 BP4

The NM_000151.4(G6PC1):c.27T>A(p.His9Gln) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,850 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: G6PC1 NM_000151.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: -0.646

Genes affected

G6PC1 (HGNC:4056): (glucose-6-phosphatase catalytic subunit 1) Glucose-6-phosphatase (G6Pase) is a multi-subunit integral membrane protein of the endoplasmic reticulum that is composed of a catalytic subunit and transporters for G6P, inorganic phosphate, and glucose. This gene (G6PC) is one of the three glucose-6-phosphatase catalytic-subunit-encoding genes in human: G6PC, G6PC2 and G6PC3. Glucose-6-phosphatase catalyzes the hydrolysis of D-glucose 6-phosphate to D-glucose and orthophosphate and is a key enzyme in glucose homeostasis, functioning in gluconeogenesis and glycogenolysis. Mutations in this gene cause glycogen storage disease type I (GSD1). This disease, also known as von Gierke disease, is a metabolic disorder characterized by severe hypoglycemia associated with the accumulation of glycogen and fat in the liver and kidneys.[provided by RefSeq, Feb 2011]

ACMG classification

Verdict is Uncertain_significance. Variant got 3 ACMG points.

• PM1: In a topological_domain Lumenal (size 27) in uniprot entity G6PC1_HUMAN there are 7 pathogenic changes around while only 0 benign (100%) in NM_000151.4
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.28891352).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
G6PC1	NM_000151.4	c.27T>A	p.His9Gln	missense_variant	1/5	ENST00000253801.7
G6PC1	NM_001270397.2	c.27T>A	p.His9Gln	missense_variant	1/5

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
G6PC1	ENST00000253801.7	c.27T>A	p.His9Gln	missense_variant	1/5	1	NM_000151.4	P1
G6PC1	ENST00000592383.5	c.27T>A	p.His9Gln	missense_variant	1/5	2
G6PC1	ENST00000585489.1	c.27T>A	p.His9Gln	missense_variant	1/4	5
G6PC1	ENST00000588481.1	n.92T>A		non_coding_transcript_exon_variant	1/2	2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461850 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 727224

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: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Sep 16, 2021

The c.27T>A (p.H9Q) alteration is located in exon 1 (coding exon 1) of the G6PC gene. This alteration results from a T to A substitution at nucleotide position 27, causing the histidine (H) at amino acid position 9 to be replaced by a glutamine (Q). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Glycogen storage disease due to glucose-6-phosphatase deficiency type IA Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Aug 24, 2021

This sequence change replaces histidine with glutamine at codon 9 of the G6PC protein (p.His9Gln). The histidine residue is highly conserved and there is a small physicochemical difference between histidine and glutamine. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals affected with G6PC-related conditions. 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) performed at Invitae indicates that this missense variant is not expected to disrupt G6PC protein function. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.39
BayesDel_addAF	Benign	-0.014	T
BayesDel_noAF	Benign	-0.26
Cadd	Benign	11
Dann	Uncertain	0.98
Eigen	Benign	-0.56
Eigen_PC	Benign	-0.57
FATHMM_MKL	Benign	0.57	D
LIST_S2	Benign	0.71	T;T;T
M_CAP	Benign	0.037	D
MetaRNN	Benign	0.29	T;T;T
MetaSVM	Benign	-0.76	T
MutationAssessor	Benign	1.6	L;L;.
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Uncertain	0.62	T
Sift4G	Benign	0.062	T;T;T
Polyphen		0.017	.;B;.
Vest4		0.38
MutPred		0.57		Loss of helix (P = 0.1299);Loss of helix (P = 0.1299);Loss of helix (P = 0.1299);
MVP		0.76
MPC		0.79
ClinPred		0.99	D
GERP RS		-1.1
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.6
Varity_R		0.49
gMVP		0.88

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.060		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: rs1597986754; hg19: chr17-41052920;