rs111033811

chr9-34649519-C-Gchr9-34649519-C-T

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 10P and 2B. PM2 PP5_Very_Strong BP4 BP7

The NM_000155.4(GALT):c.1014C>G(p.Gly338=) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000616 in 1,461,884 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. G338G) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 0.0000062 (0 hom.)
• Consequence: GALT NM_000155.4 synonymous
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:6
• Conservation: PhyloP100: 1.65

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 Likely_pathogenic. Variant got 8 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 9-34649519-C-G is Pathogenic according to our data. Variant chr9-34649519-C-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 25316.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.38).. Strength limited to SUPPORTING due to the PP5.
• BP7: Synonymous conserved (PhyloP=1.65 with no splicing effect.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GALT	NM_000155.4	c.1014C>G	p.Gly338=	synonymous_variant	10/11	ENST00000378842.8
GALT	NM_001258332.2	c.687C>G	p.Gly229=	synonymous_variant	8/9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GALT	ENST00000378842.8	c.1014C>G	p.Gly338=	synonymous_variant	10/11	1	NM_000155.4	P1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD3 exomes AF: 0.0000119 AC: 3 AN: 251480 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135916

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: 0.0000264

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000616 AC: 9 AN: 1461884 Hom.: 0 Cov.: 31 AF XY: 0.00000550 AC XY: 4 AN XY: 727242

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: 0.00000719

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 31

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:3

Likely pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Oct 27, 2023	Variant summary: GALT c.1014C>G alters a non-conserved nucleotide resulting in a synonymous change. Several computational tools predict a significant impact on normal splicing: Three predict the variant creates a cryptic 5' donor site. At least one publication reports experimental evidence that this variant affects mRNA splicing leading to a frameshift with a premature stop codon at nt1027 (p.Tyr339Leufs*5) (example: Boutron_2012). The variant allele was found at a frequency of 1.2e-05 in 251480 control chromosomes (gnomAD). c.1014C>G has been reported in the literature in individuals affected with Galactosemia (examples: Boutron_2012, Lacombe_2015, Yuzyuk_2018 and Jezela-Stanek_2021). The following publications have been ascertained in the context of this evaluation (PMID: 22944367, 34030713, 31194895, 25622686). Three submitters have cited clinical-significance assessments for this variant to ClinVar after 2014. All submitters classified the variant as pathogenic/likely pathogenic. Based on the evidence outlined above, the variant was classified as likely pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	May 31, 2023	- -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Dec 01, 2023	This sequence change affects codon 338 of the GALT mRNA. It is a 'silent' change, meaning that it does not change the encoded amino acid sequence of the GALT protein. RNA analysis indicates that this variant induces altered splicing and likely disrupts the C-terminus of the protein. This variant is present in population databases (rs111033811, gnomAD 0.003%). This variant has been observed in individual(s) with galactosemia (PMID: 22944367; Invitae). ClinVar contains an entry for this variant (Variation ID: 25316). Studies have shown that this variant results in activation of a new donor splice site in exon 10 and introduces a new termination codon (PMID: 22944367). However the mRNA is not expected to undergo nonsense-mediated decay. For these reasons, this variant has been classified as Pathogenic. -

not provided Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Mayo Clinic Laboratories, Mayo Clinic	Sep 02, 2022	PP4, PM2, PM3_strong, PS3, PS4 -
Likely pathogenic, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Sep 18, 2015	- -

Galactosemia Pathogenic:1

Likely pathogenic, no assertion criteria provided

clinical testing

Natera, Inc.

Mar 15, 2017

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.38
Cadd	Benign	19
Dann	Benign	0.77
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.54		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.54		Position offset: -1
DS_DL_spliceai		0.35		Position offset: 45

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

Publications

LitVar

Other links and lift over

dbSNP: rs111033811; hg19: chr9-34649516;