NM_000155.4:c.1018G>A

Variant names:

• chr9-34649523-G-A
• rs111033806
• NM_000155.4:c.1018G>A

Variant summary

Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PM2 PP3_Strong PP5

The NM_000155.4(GALT):​c.1018G>A​(p.Glu340Lys) variant causes a missense change. The variant allele was found at a frequency of 0.0000197 in 152,304 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency: Genomes: 𝑓 0.000020 (0 hom., cov: 31)
• Consequence: GALT NM_000155.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:3
• Conservation: PhyloP100: 5.17

Genes affected

GALT (HGNC:4135): (galactose-1-phosphate uridylyltransferase) Galactose-1-phosphate uridyl transferase (GALT) catalyzes the second step of the Leloir pathway of galactose metabolism, namely the conversion of UDP-glucose + galactose-1-phosphate to glucose-1-phosphate + UDP-galactose. The absence of this enzyme results in classic galactosemia in humans and can be fatal in the newborn period if lactose is not removed from the diet. The pathophysiology of galactosemia has not been clearly defined. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Apr 2012]

ENSG00000258728 (HGNC:):

ACMG classification

Verdict is Likely_pathogenic. Variant got 7 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.992
• PP5: Variant 9-34649523-G-A is Pathogenic according to our data. Variant chr9-34649523-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 25317.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=1, Uncertain_significance=2}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GALT	NM_000155.4	c.1018G>A	p.Glu340Lys	missense_variant	Exon 10 of 11	ENST00000378842.8	NP_000146.2
GALT	NM_001258332.2	c.691G>A	p.Glu231Lys	missense_variant	Exon 8 of 9		NP_001245261.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GALT	ENST00000378842.8	c.1018G>A	p.Glu340Lys	missense_variant	Exon 10 of 11	1	NM_000155.4	ENSP00000368119.4
ENSG00000258728	ENST00000556278.1	c.432+1067G>A		intron_variant	Intron 4 of 7	5		ENSP00000451792.1

Frequencies

GnomAD3 genomes AF: 0.0000197 AC: 3 AN: 152186 Hom.: 0 Cov.: 31

Gnomad AFR AF: 0.0000483

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.000207

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 31

GnomAD4 genome AF: 0.0000197 AC: 3 AN: 152304 Hom.: 0 Cov.: 31 AF XY: 0.0000134 AC XY: 1 AN XY: 74484

Gnomad4 AFR AF: 0.0000481

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.000207

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000329 Hom.: 0

Bravo AF: 0.0000302

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:3

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Deficiency of UDPglucose-hexose-1-phosphate uridylyltransferase Pathogenic:1 Uncertain:1

Oct 21, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces glutamic acid, which is acidic and polar, with lysine, which is basic and polar, at codon 340 of the GALT protein (p.Glu340Lys). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with GALT-related conditions (PMID: 10649501, 20213376, 22944367, 28065439). ClinVar contains an entry for this variant (Variation ID: 25317). 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 expected to disrupt GALT 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. -

Jun 12, 2023

Baylor Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not specified Uncertain:1

Aug 26, 2021

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: GALT c.1018G>A (p.Glu340Lys) results in a conservative amino acid change located in the Galactose-1-phosphate uridyl transferase, C-terminal domain of the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 251462 control chromosomes. c.1018G>A has been reported in the literature in individuals affected with Galactosemia in the homozygous and compound heterozygous state with the Duarte allele in cis (Kozak_2000, Milankovics_2010), the compound heterozygous without reporting the of presence of Duarte allele (Siripunthana_2013) and in the heterozygous state without a reported second allele and unknown Duarte allele status (Welling_2017). The penetrance of the variant in isolation is unknown. Additionally, to our knowledge, no experimental studies have been performed on this variant in isolation. One clinical diagnostic laboratory has submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. One laboratory classified the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as VUS-possibly pathogenic. -

Galactosemia Uncertain:1

Aug 10, 2021

Natera, Inc.

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.56	D
BayesDel_noAF	Pathogenic	0.56
CADD	Pathogenic	33
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.98	.;D
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.95
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	1.0	D;D
M_CAP	Pathogenic	0.80	D
MetaRNN	Pathogenic	0.99	D;D
MetaSVM	Pathogenic	0.99	D
MutationAssessor	Pathogenic	4.0	.;H
PrimateAI	Pathogenic	0.91	D
PROVEAN	Uncertain	-3.9	D;D
REVEL	Pathogenic	0.98
Sift	Pathogenic	0.0	D;D
Sift4G	Pathogenic	0.0010	D;D
Polyphen		1.0	.;D
Vest4		0.95
MutPred		0.95		.;Gain of MoRF binding (P = 0.0031);
MVP		0.99
MPC		0.35
ClinPred		1.0	D
GERP RS		5.2
Varity_R		0.99
gMVP		0.96

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: rs111033806; hg19: chr9-34649520; COSMIC: COSV58840206; COSMIC: COSV58840206;