NM_000155.4:c.197C>T

Variant names:

Variant summary

Our verdict is Likely pathogenic. The variant received 9 ACMG points: 9P and 0B. PM1PM2PP2PP3_Strong

The NM_000155.4(GALT):c.197C>T(p.Pro66Leu) variant causes a missense change. The variant allele was found at a frequency of 0.0000384 in 1,614,060 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 Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. P66H) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.000033 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000039 ( 0 hom. )

Consequence

GALT
NM_000155.4 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:6

Conservation

PhyloP100: 5.59

Publications

6 publications found

Variant links:

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

GALT links:

ENSG00000258728 (HGNC:):

ENSG00000258728 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_pathogenic. The variant received 9 ACMG points.

PM1

In a hotspot region, there are 6 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 2 benign, 9 uncertain in NM_000155.4

PM2

Very rare variant in population databases, with high coverage;

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, 0.952

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.197C>T	p.Pro66Leu	missense	Exon 2 of 11	NP_000146.2
	GALT	NM_001258332.2		c.-6C>T		5_prime_UTR	Exon 2 of 9	NP_001245261.1

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
GALT	ENST00000378842.8	TSL:1 MANE Select	c.197C>T	p.Pro66Leu	missense	Exon 2 of 11	ENSP00000368119.4
ENSG00000258728	ENST00000556278.1	TSL:5	c.197C>T	p.Pro66Leu	missense	Exon 2 of 8	ENSP00000451792.1
GALT	ENST00000465543.6	TSL:2	n.536C>T		non_coding_transcript_exon	Exon 1 of 5

Frequencies

GnomAD3 genomes

AF:

0.0000328

AC:

AN:

152210

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000735

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000318

AC:

AN:

251350

AF XY:

0.0000294

show subpopulations

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 FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000704

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000390

AC:

AN:

1461850

Hom.:

Cov.:

AF XY:

0.0000440

AC XY:

AN XY:

727220

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33480

American (AMR)

AF:

0.00

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.00

AC:

AN:

39700

South Asian (SAS)

AF:

0.0000116

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53388

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.0000477

AC:

AN:

1112000

Other (OTH)

AF:

0.0000497

AC:

AN:

60396

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.491

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000328

AC:

AN:

152210

Hom.:

Cov.:

AF XY:

0.0000672

AC XY:

AN XY:

74362

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41466

American (AMR)

AF:

0.00

AC:

AN:

15278

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5186

South Asian (SAS)

AF:

0.00

AC:

AN:

4832

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10624

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.0000735

AC:

AN:

68032

Other (OTH)

AF:

0.00

AC:

AN:

2092

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.535

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.0000689

Hom.:

Bravo

AF:

0.0000302

ESP6500AA

AF:

0.00

AC:

ESP6500EA

AF:

0.000349

AC:

ExAC

AF:

0.0000576

AC:

EpiCase

AF:

0.000218

EpiControl

AF:

0.00

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:6

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Deficiency of UDPglucose-hexose-1-phosphate uridylyltransferase

Uncertain:2

Oct 01, 2021

Myriad Genetics, Inc.

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

NM_000155.3(GALT):c.197C>T(P66L) is a missense variant classified as a variant of uncertain significance in the context of galactosemia. P66L has not been observed in cases with relevant disease. Functional assessments of this variant are available in the literature (PMID: 31267113). P66L has been observed in population frequency databases (gnomAD: NFE 0.01%). In summary, there is insufficient evidence to classify NM_000155.3(GALT):c.197C>T(P66L) as pathogenic or benign. Please note: this variant was assessed in the context of healthy population screening.

Nov 03, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces proline, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 66 of the GALT protein (p.Pro66Leu). This variant is present in population databases (rs111033656, gnomAD 0.009%). This missense change has been observed in individual(s) with a positive newborn screening result for GALT-related disease (PMID: 25087612; Invitae). ClinVar contains an entry for this variant (Variation ID: 25136). 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 with a positive predictive value of 95%. 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.

not specified

Uncertain:1

Feb 15, 2019

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.197C>T (p.Pro66Leu) results in a non-conservative amino acid change located in the Galactose-1-phosphate uridyl transferase, N-terminal domain of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 4e-05 in 277122 control chromosomes. This frequency is not higher than expected for a pathogenic variant in GALT causing Galactosemia (4e-05 vs 0.0029), allowing no conclusion about variant significance. A publication reports a compound heterozygote patient (Shin 2004), who carried the variant c.197C>A that would cause a missense change of Pro66His however, in the report a missense change of Pro66Leu is indicated. Authors do not provide sequence data therefore it remains unclear whether it is the variant of interest that was reported. A ClinVar submission from a clinical diagnostic laboratory (evaluation after 2014) cites the variant as uncertain significance. However, another well-established clinical diagnostic laboratory, ARUP, has classified the variant as pathogenic prior to 2014. Furthermore, another variant, c.197C>A, affecting the same nucleotide but causing a different missense change, Pro66His has been reported in ClinVar, along with additional variants affecting nearby residues, p.R67C, p.R67H, p.H68P, suggesting the region is important for GALT function. Based on the evidence outlined above, the variant was classified as VUS-possibly pathogenic.

GALT-related disorder

Uncertain:1

Mar 08, 2024

PreventionGenetics, part of Exact Sciences

Significance:Uncertain significance

Review Status:no assertion criteria provided

Collection Method:clinical testing

The GALT c.197C>T variant is predicted to result in the amino acid substitution p.Pro66Leu. This variant has been reported in the compound heterozygous state in a patient with galactosemia and in at least one individual as part of newborn screening (Shin et al. 2004. PubMed ID: 15633893, Tabor et al. 2014. PubMed ID: 25087612). This variant is reported in 0.0070% of alleles in individuals of European (Non-Finnish) descent in gnomAD. Although we suspect that this variant may be pathogenic, at this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence.

Galactosemia

Uncertain:1

Sep 16, 2020

Natera, Inc.

Significance:Uncertain significance

Review Status:no assertion criteria provided

Collection Method:clinical testing

not provided

Uncertain:1

Nov 10, 2022

Mayo Clinic Laboratories, Mayo Clinic

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

PP3, PM2

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.13

BayesDel_addAF

Pathogenic

0.39

BayesDel_noAF

Pathogenic

0.52

CADD

Pathogenic

(source)

DANN

Uncertain

1.0

DEOGEN2

Pathogenic

0.93

Eigen

Pathogenic

0.75

Eigen_PC

Pathogenic

0.71

FATHMM_MKL

Uncertain

0.94

LIST_S2

Benign

0.83

M_CAP

Pathogenic

0.31

MetaRNN

Pathogenic

0.95

MetaSVM

Pathogenic

1.1

MutationAssessor

Pathogenic

2.9

PhyloP100

5.6

PrimateAI

Uncertain

0.61

PROVEAN

Pathogenic

-7.6

REVEL

Pathogenic

0.91

Sift

Uncertain

0.028

Sift4G

Uncertain

0.038

Polyphen

0.99

Vest4

0.90

MVP

0.99

MPC

1.8

ClinPred

0.95

GERP RS

4.6

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

Varity_R

0.84

gMVP

0.95

Mutation Taster

=139/161

disease causing

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over