rs111033802

chr9-34649488-G-A

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PM1 PM2 PM5 PP3_Strong PP5_Very_Strong

The NM_000155.4(GALT):c.983G>A(p.Arg328His) variant causes a missense change. The variant allele was found at a frequency of 0.00000867 in 1,614,006 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 12/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R328C) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 31)
  • Exomes 𝑓: 0.0000082 (0 hom.)
• Consequence: GALT NM_000155.4 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4
• 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]

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PM1: In a hotspot region, there are 9 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 4 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 chr9-34649487-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 381664.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.987
• PP5: Variant 9-34649488-G-A is Pathogenic according to our data. Variant chr9-34649488-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 25309.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr9-34649488-G-A is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GALT	NM_000155.4	c.983G>A	p.Arg328His	missense_variant	10/11	ENST00000378842.8
GALT	NM_001258332.2	c.656G>A	p.Arg219His	missense_variant	8/9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GALT	ENST00000378842.8	c.983G>A	p.Arg328His	missense_variant	10/11	1	NM_000155.4	P1

Frequencies

GnomAD3 genomes AF: 0.0000131 AC: 2 AN: 152138 Hom.: 0 Cov.: 31

Gnomad AFR AF: 0.0000241

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: 0.0000147

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251464 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135906

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: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000879

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000821 AC: 12 AN: 1461868 Hom.: 0 Cov.: 31 AF XY: 0.00000825 AC XY: 6 AN XY: 727236

Gnomad4 AFR exome AF: 0.0000299

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: 0.00000989

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.0000131 AC: 2 AN: 152138 Hom.: 0 Cov.: 31 AF XY: 0.0000269 AC XY: 2 AN XY: 74312

Gnomad4 AFR AF: 0.0000241

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000147

Gnomad4 OTH AF: 0.00

ExAC AF: 0.00000824 AC: 1

EpiCase AF: 0.00

EpiControl AF: 0.0000593

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Deficiency of UDPglucose-hexose-1-phosphate uridylyltransferase Pathogenic:3

Likely pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Nov 26, 2018	Variant summary: GALT c.983G>A (p.Arg328His) results in a non-conservative amino acid change located in the Galactose-1-phosphate uridyl transferase, C-terminal domain of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function, including one computational study that considers the Arg328 H-bond with Arg-51 essential for protein function (Facchiano_2009). The variant allele was found at a frequency of 4.1e-06 in 246246 control chromosomes (gnomAD). The variant, c.983G>A, has been reported in the literature in individuals affected with Galactosemia, including a homozygote (Ozgul_2013, Elsas_1998). These data indicate that the variant may be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014, with one lab calling it pathogenic in 2012. A different variant affecting the same codon, c.982C>T (p.Arg328Cys), was classified as likely pathogenic internally, suggesting this codon could play an important role in protein function. Based on the evidence outlined above, the variant was classified as likely pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	-	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Invitae	Jan 29, 2024	This sequence change replaces arginine, which is basic and polar, with histidine, which is basic and polar, at codon 328 of the GALT protein (p.Arg328His). This variant is present in population databases (rs111033802, gnomAD 0.0009%). This missense change has been observed in individual(s) with clinical features of galactosemia (PMID: 33101984). ClinVar contains an entry for this variant (Variation ID: 25309). 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%. This variant disrupts the p.Arg328 amino acid residue in GALT. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 20663501). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

Galactosemia Pathogenic:1

Likely pathogenic, no assertion criteria provided

clinical testing

Natera, Inc.

Sep 16, 2020

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.91
BayesDel_addAF	Pathogenic	0.56	D
BayesDel_noAF	Pathogenic	0.56
Cadd	Pathogenic	30
Dann	Pathogenic	1.0
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	0.97
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	1.0	D;D
M_CAP	Pathogenic	0.69	D
MetaRNN	Pathogenic	0.99	D;D
MetaSVM	Pathogenic	0.97	D
MutationTaster	Benign	1.0	A;A
PrimateAI	Pathogenic	0.80	T
PROVEAN	Pathogenic	-4.9	D;D
REVEL	Pathogenic	0.99
Sift	Pathogenic	0.0	D;D
Sift4G	Pathogenic	0.0	D;D
Polyphen		1.0	.;D
Vest4		0.89
MutPred		0.91		.;Loss of MoRF binding (P = 0.0269);
MVP		0.99
MPC		0.36
ClinPred		0.99	D
GERP RS		5.3
Varity_R		0.96
gMVP		0.79

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: rs111033802; hg19: chr9-34649485; COSMIC: COSV100535360; COSMIC: COSV100535360;