chr17-80117008-C-T

Position:

• chr17-80117008-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 4P and 2B. PM1 PM2 BP4_Moderate

The NM_000152.5(GAA):​c.2230C>T​(p.Leu744Phe) 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 1,461,422 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 16/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Synonymous variant affecting the same amino acid position (i.e. L744L) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: GAA NM_000152.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 2.29

Genes affected

GAA (HGNC:4065): (alpha glucosidase) This gene encodes lysosomal alpha-glucosidase, which is essential for the degradation of glycogen to glucose in lysosomes. The encoded preproprotein is proteolytically processed to generate multiple intermediate forms and the mature form of the enzyme. Defects in this gene are the cause of glycogen storage disease II, also known as Pompe's disease, which is an autosomal recessive disorder with a broad clinical spectrum. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Jan 2016]

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 3 benign, 8 uncertain in NM_000152.5
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.24060181).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GAA	NM_000152.5	c.2230C>T	p.Leu744Phe	missense_variant	16/20	ENST00000302262.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GAA	ENST00000302262.8	c.2230C>T	p.Leu744Phe	missense_variant	16/20	1	NM_000152.5	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000399 AC: 1 AN: 250916 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135790

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: 0.0000327

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461422 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727032

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: 0.0000116

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Glycogen storage disease, type II Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 24, 2021

This sequence change replaces leucine with phenylalanine at codon 744 of the GAA protein (p.Leu744Phe). The leucine residue is moderately conserved and there is a small physicochemical difference between leucine and phenylalanine. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals affected with GAA-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Tolerated"; PolyPhen-2: "Benign"; Align-GVGD: "Class C0". The phenylalanine amino acid residue is found in multiple mammalian species, which suggests that this missense change does not adversely affect 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	Benign	0.083
BayesDel_addAF	Benign	-0.084	T
BayesDel_noAF	Benign	-0.26
CADD	Benign	18
DANN	Benign	0.32
DEOGEN2	Uncertain	0.48	T;T
Eigen	Benign	-0.61
Eigen_PC	Benign	-0.29
FATHMM_MKL	Benign	0.67	D
LIST_S2	Benign	0.79	.;T
M_CAP	Benign	0.054	D
MetaRNN	Benign	0.24	T;T
MetaSVM	Benign	-0.68	T
MutationAssessor	Benign	-2.0	N;N
MutationTaster	Benign	0.99	D;D
PrimateAI	Benign	0.43	T
PROVEAN	Benign	4.4	N;N
REVEL	Benign	0.22
Sift	Benign	1.0	T;T
Sift4G	Benign	1.0	T;T
Polyphen		0.0010	B;B
Vest4		0.32
MutPred		0.64		Gain of phosphorylation at T739 (P = 0.2816);Gain of phosphorylation at T739 (P = 0.2816);
MVP		0.69
MPC		0.12
ClinPred		0.23	T
GERP RS		4.0
Varity_R		0.16
gMVP		0.65

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: rs1347832021; hg19: chr17-78090807;