rs111033669

Positions:

• chr9-34647529-A-G
• chr9-34647529-A-T

Variant summary

Our verdict is Pathogenic. Variant got 14 ACMG points: 14P and 0B. PM2 PP3_Strong PP5_Very_Strong

The NM_000155.4(GALT):​c.290A>G​(p.Asn97Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000342 in 1,461,892 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 Likely pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000034 (0 hom.)
• Consequence: GALT NM_000155.4 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:6
• Conservation: PhyloP100: 8.36

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 Pathogenic. Variant got 14 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.992
• PP5: Variant 9-34647529-A-G is Pathogenic according to our data. Variant chr9-34647529-A-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 25146.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
GALT	NM_000155.4	c.290A>G	p.Asn97Ser	missense_variant	3/11	ENST00000378842.8	NP_000146.2
GALT	NM_001258332.2	c.50+271A>G		intron_variant			NP_001245261.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
GALT	ENST00000378842.8	c.290A>G	p.Asn97Ser	missense_variant	3/11	1	NM_000155.4	ENSP00000368119.4
ENSG00000258728	ENST00000556278.1	c.252+271A>G		intron_variant		5		ENSP00000451792.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251494 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135922

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: 0.00000342 AC: 5 AN: 1461892 Hom.: 0 Cov.: 32 AF XY: 0.00000413 AC XY: 3 AN XY: 727248

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000504

Gnomad4 SAS exome AF: 0.0000116

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 8.99e-7

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:6

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Deficiency of UDPglucose-hexose-1-phosphate uridylyltransferase Pathogenic:4

Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Jul 22, 2023	- -
Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Sep 06, 2019	Variant summary: GALT c.290A>G (p.Asn97Ser, legacy name c.318A>G) results in a conservative amino acid change located in the Galactose-1-phosphate uridyl transferase, N-terminal domain (IPR005849) of the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. Several computational tools predict a significant impact on normal splicing: Five predict the variant creates a cryptic 3 acceptor site. A functional study, Ashino_1995 found the variant supports these predictions. The variant allele was found at a frequency of 4e-06 in 251494 control chromosomes (gnomAD). c.290A>G has been reported in the literature in individuals affected with Galactosemia (eg. Ashino_1995, Shin_2004, Waisbren_2012). These data indicate that the variant is likely to be associated with disease. At least one publication reports experimental evidence evaluating an impact on protein function. The most pronounced variant effect results in <10% of normal activity (eg. Ashino_1995). A ClinVar submission (evaluation after 2014) cites the variant as likely pathogenic. Furthermore, another variant affecting the same codon, N97D, and nearby codons, F95L, D98N, D98H, have been reported in association with Galactosaemia (via HGMD). Therefore, suggesting this region is important for GALT protein function. Based on the evidence outlined above, the variant was classified as pathogenic. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Mar 28, 2022	- -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Nov 19, 2023	This sequence change replaces asparagine, which is neutral and polar, with serine, which is neutral and polar, at codon 97 of the GALT protein (p.Asn97Ser). This variant is present in population databases (rs111033669, gnomAD 0.0009%). This missense change has been observed in individual(s) with classic galactosemia (PMID: 7550229, 15633893). This variant is also known as 318A>G. ClinVar contains an entry for this variant (Variation ID: 25146). 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%. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. This variant disrupts the p.Asn97 amino acid residue in GALT. Other variant(s) that disrupt this residue have been observed in individuals with GALT-related conditions (PMID: 22944367), which suggests that this may be a clinically significant amino acid residue. For these reasons, this variant has been classified as Pathogenic. -

GALT-related disorder Pathogenic:1

Pathogenic, no assertion criteria provided

clinical testing

PreventionGenetics, part of Exact Sciences

May 10, 2024

The GALT c.290A>G variant is predicted to result in the amino acid substitution p.Asn97Ser. This variant, also referred to as c.318A>G using legacy nomenclature, has been reported in the homozygous and compound heterozygous states in multiple individuals with galactosemia (see for example, Table 1, Ashino et al. 1995. PubMed ID: 7550229; Table 3, Shin and Podskarbi. 2004. PubMed ID: 15633893; Table 2, Waisbren et al. 2011. PubMed ID: 21779791). An RT-PCR study suggests this variant impacts mRNA splicing via using of a cryptic splice acceptor site and leads to a frameshift loss-of-function effect (Figure 2, Ashino et al. 1995. PubMed ID: 7550229). This variant is reported in 0.00088% of alleles in individuals of European (non-Finnish) descent in gnomAD. This variant is interpreted as pathogenic. -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Eurofins Ntd Llc (ga)

Jan 17, 2013

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.79
BayesDel_addAF	Pathogenic	0.30	D
BayesDel_noAF	Pathogenic	0.19
CADD	Pathogenic	32
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.99	D
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.92
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Pathogenic	1.0	D
M_CAP	Pathogenic	0.73	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	3.9	H
PrimateAI	Uncertain	0.58	T
PROVEAN	Pathogenic	-4.6	D
REVEL	Pathogenic	0.84
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0010	D
Polyphen		1.0	D
Vest4		0.94
MutPred		0.94		Gain of glycosylation at N97 (P = 0.0155);
MVP		0.99
MPC		1.7
ClinPred		1.0	D
GERP RS		5.5
Varity_R		0.94
gMVP		0.99

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.30		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.30		Position offset: 1
DS_AL_spliceai		0.24		Position offset: -37

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs111033669; hg19: chr9-34647526;