9-34649041-C-T
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Variant summary
Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2
The NM_000155.4(GALT):c.864C>T(p.Asn288Asn) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000026 in 1,613,992 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 Uncertain significance (★★).
Frequency
Genomes: 𝑓 0.000092 ( 0 hom., cov: 32)
Exomes 𝑓: 0.000019 ( 0 hom. )
Consequence
GALT
NM_000155.4 synonymous
NM_000155.4 synonymous
Scores
2
Clinical Significance
Conservation
PhyloP100: -0.186
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]
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ACMG classification
Classification made for transcript
Verdict is Uncertain_significance. Variant got 2 ACMG points.
PM2
Very rare variant in population databases, with high coverage;
Transcripts
RefSeq
Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | MANE | Protein | UniProt |
---|---|---|---|---|---|---|---|---|
GALT | NM_000155.4 | c.864C>T | p.Asn288Asn | synonymous_variant | 9/11 | ENST00000378842.8 | NP_000146.2 | |
GALT | NM_001258332.2 | c.537C>T | p.Asn179Asn | synonymous_variant | 7/9 | NP_001245261.1 |
Ensembl
Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | TSL | MANE | Protein | Appris | UniProt |
---|---|---|---|---|---|---|---|---|---|---|
GALT | ENST00000378842.8 | c.864C>T | p.Asn288Asn | synonymous_variant | 9/11 | 1 | NM_000155.4 | ENSP00000368119.4 | ||
ENSG00000258728 | ENST00000556278.1 | c.432+585C>T | intron_variant | 5 | ENSP00000451792.1 |
Frequencies
GnomAD3 genomes AF: 0.0000920 AC: 14AN: 152118Hom.: 0 Cov.: 32
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GnomAD3 exomes AF: 0.0000437 AC: 11AN: 251492Hom.: 0 AF XY: 0.0000441 AC XY: 6AN XY: 135922
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GnomAD4 exome AF: 0.0000192 AC: 28AN: 1461874Hom.: 0 Cov.: 32 AF XY: 0.0000261 AC XY: 19AN XY: 727232
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GnomAD4 genome AF: 0.0000920 AC: 14AN: 152118Hom.: 0 Cov.: 32 AF XY: 0.000108 AC XY: 8AN XY: 74306
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ClinVar
Significance: Uncertain significance
Submissions summary: Uncertain:7
Revision: criteria provided, multiple submitters, no conflicts
LINK: link
Submissions by phenotype
Deficiency of UDPglucose-hexose-1-phosphate uridylyltransferase Uncertain:3
Uncertain significance, criteria provided, single submitter | clinical testing | Counsyl | May 12, 2017 | - - |
Uncertain significance, criteria provided, single submitter | clinical testing | Mendelics | Jun 02, 2023 | - - |
Uncertain significance, criteria provided, single submitter | clinical testing | Labcorp Genetics (formerly Invitae), Labcorp | May 17, 2022 | This sequence change affects codon 288 of the GALT mRNA. It is a 'silent' change, meaning that it does not change the encoded amino acid sequence of the GALT protein. This variant is present in population databases (rs372134800, gnomAD 0.03%). This variant has been observed in individual(s) with features of galactosemia (PMID: 22944367). ClinVar contains an entry for this variant (Variation ID: 203732). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant is not likely to affect RNA splicing. 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:2
Uncertain significance, criteria provided, single submitter | clinical testing | Women's Health and Genetics/Laboratory Corporation of America, LabCorp | Jul 29, 2019 | Variant summary: GALT c.864C>T alters a non-conserved nucleotide resulting in a synonymous change. Several computational tools predict a significant impact on normal splicing: One predict the variant strengthens a cryptic 3 acceptor site. However, these predictions have yet to be confirmed by functional studies. The variant allele was found at a frequency of 4.4e-05 in 251692 control chromosomes (gnomAD). This frequency is not significantly higher than expected for a pathogenic variant in GALT causing Galactosemia (4.4e-05 vs 0.0029), allowing no conclusion about variant significance. The variant, c.864C>T, has been reported in the literature in two compound heterozygous individuals affected with Galactosemia (McDonald_2009, Boutron_2012). One of these reports also noted that the diagnosis was confirmed by absent GALT activity in erythrocytes in all their cases, though no patient specific data were provided (Boutron 2012). The variant has also been reported in homozygosity in a sample from an individual that had only a residual GALT activity; and although no information was provided on the patient's phenotype, the measured enzyme activity was specific for galactosemia (Yuzyuk_2018). A conference abstract (McDonald 2009) described that cDNA containing the variant of interest (from a proband and probands father) was void of exon 9, although they both had additional variants leading to a complex haplotype (N288N, T292T and H315H) and it is not clear if the exon skipping effect was caused solely by our variant of interest or a combination effect due to this specific haplotype. These data indicate that the variant may be associated with disease. Three ClinVar submissions from other clinical diagnostic laboratories (evaluation after 2014) cited the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as VUS-possibly pathogenic until more information becomes available. - |
Uncertain significance, criteria provided, single submitter | clinical testing | ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories | Feb 14, 2017 | - - |
Galactosemia Uncertain:1
Uncertain significance, no assertion criteria provided | clinical testing | Natera, Inc. | Sep 16, 2020 | - - |
not provided Uncertain:1
Uncertain significance, criteria provided, single submitter | clinical testing | Mayo Clinic Laboratories, Mayo Clinic | Aug 30, 2021 | - - |
Computational scores
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Name
Calibrated prediction
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BayesDel_noAF
Benign
CADD
Benign
DANN
Benign
RBP_binding_hub_radar
RBP_regulation_power_radar
Splicing
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SpliceAI score (max)
Details are displayed if max score is > 0.2
DS_DL_spliceai
Position offset: 40
Find out detailed SpliceAI scores and Pangolin per-transcript scores at