9-34647956-G-T

Variant names:

• chr9-34647956-G-T
• rs367543258
• NM_000155.4:c.502G>T

Variant summary

Our verdict is Pathogenic. The variant received 17 ACMG points: 17P and 0B. PM1 PM2 PM5 PP2 PP3_Moderate PP5_Very_Strong

The NM_000155.4(GALT):​c.502G>T​(p.Val168Leu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,890 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 Pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. V168M) has been classified as Pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: GALT NM_000155.4 missense
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:6
• Conservation: PhyloP100: 8.87
• Publications: 11 publications found

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]

GALT Gene-Disease associations (from GenCC):

• classic galactosemia

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), G2P, Orphanet
• galactosemia

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen, Myriad Women’s Health

ENSG00000258728 (HGNC:):

ACMG classification

Our verdict: Pathogenic. The variant received 17 ACMG points.

• PM1: In a hotspot region, there are 6 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 10 uncertain in NM_000155.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr9-34647956-G-A is described in ClinVar as Pathogenic. ClinVar VariationId is 371128.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 104 curated pathogenic missense variants (we use a threshold of 10). The gene has 17 curated benign missense variants. Gene score misZ: 0.91493 (below the threshold of 3.09). Trascript score misZ: 1.8645 (below the threshold of 3.09). GenCC associations: The gene is linked to galactosemia, classic galactosemia.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.907
• PP5: Variant 9-34647956-G-T is Pathogenic according to our data. Variant chr9-34647956-G-T is described in ClinVar as Pathogenic. ClinVar VariationId is 25189.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000155.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GALT	NM_000155.4	MANE Select	c.502G>T	p.Val168Leu	missense	Exon 5 of 11	NP_000146.2
	GALT	NM_001258332.2		c.175G>T	p.Val59Leu	missense	Exon 3 of 9	NP_001245261.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GALT	ENST00000378842.8	TSL:1 MANE Select	c.502G>T	p.Val168Leu	missense	Exon 5 of 11	ENSP00000368119.4
	ENSG00000258728	ENST00000556278.1	TSL:5	c.253-159G>T		intron	N/A	ENSP00000451792.1
	GALT	ENST00000450095.6	TSL:2	c.175G>T	p.Val59Leu	missense	Exon 3 of 9	ENSP00000401956.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461890 Hom.: 0 Cov.: 33 AF XY: 0.00000138 AC XY: 1 AN XY: 727248

African (AFR) AF: 0.00 AC: 0 AN: 33478

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53420

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1112010

Other (OTH) AF: 0.0000166 AC: 1 AN: 60396

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:6

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Deficiency of UDPglucose-hexose-1-phosphate uridylyltransferase Pathogenic:5

Oct 23, 2023

Baylor Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Jul 11, 2014

Counsyl

Significance: Likely pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

This submission and the accompanying classification are no longer maintained by the submitter. For more information on current observations and classification, please contact variantquestions@myriad.com.

May 29, 2024

Fulgent Genetics, Fulgent Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Nov 15, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces valine, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 168 of the GALT protein (p.Val168Leu). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with galactosemia (PMID: 22461411, 24045215). ClinVar contains an entry for this variant (Variation ID: 25189). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is expected to disrupt GALT protein function with a positive predictive value of 95%. Experimental studies have shown that this missense change affects GALT function (PMID: 22461411). For these reasons, this variant has been classified as Pathogenic.

May 28, 2024

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

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: GALT c.502G>T (p.Val168Leu) results in a conservative amino acid change located in the galactose-1-phosphate uridyl transferase, N-terminal domain (IPR005849) of the encoded protein sequence. Three of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 251446 control chromosomes. c.502G>T has been reported in the literature in the the homozygous and compound heterozygous states in individuals affected with Galactosemia (e.g. Estrada_2013, Tang_2012). These data indicate that the variant is likely to be associated with disease. At least one publication reports experimental evidence that this variant results in absent enzyme activity in vitro (e.g. Tang_2012). The following publications have been ascertained in the context of this evaluation (PMID: 24045215, 22461411). ClinVar contains an entry for this variant (Variation ID: 25189). Based on the evidence outlined above, the variant was classified as pathogenic.

Galactosemia Pathogenic:1

Aug 26, 2021

Natera, Inc.

Significance: Likely pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.70
BayesDel_addAF	Pathogenic	0.54	D
BayesDel_noAF	Pathogenic	0.54
CADD	Pathogenic	28
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.97	D
Eigen	Pathogenic	0.88
Eigen_PC	Pathogenic	0.84
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.98	D
M_CAP	Pathogenic	0.51	D
MetaRNN	Pathogenic	0.91	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Uncertain	2.1	M
PhyloP100		8.9
PrimateAI	Uncertain	0.66	T
PROVEAN	Uncertain	-2.9	D
REVEL	Pathogenic	0.89
Sift	Uncertain	0.0010	D
Sift4G	Benign	0.074	T
Polyphen		0.98	D
Vest4		0.75
MutPred		0.75		Loss of sheet (P = 0.302)
MVP		0.99
MPC		1.8
ClinPred		0.98	D
GERP RS		5.3
Varity_R		0.76
gMVP		0.95
Mutation Taster		=3/97	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.13		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: rs367543258; hg19: chr9-34647953;