NM_000155.4:c.91C>A

Variant names:

• chr9-34647097-C-A
• rs111033643
• NM_000155.4:c.91C>A

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PM1 PM2 PP2 PP3_Strong PP5

The NM_000155.4(GALT):​c.91C>A​(p.His31Asn) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency: Genomes: not found (cov: 32)
• Consequence: GALT NM_000155.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:2
• Conservation: PhyloP100: 7.28
• Publications: 2 publications found

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

ENSG00000258728 (HGNC:):

ACMG classification

Our verdict: Pathogenic. The variant received 10 ACMG points.

• PM1: In a hotspot region, there are 7 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 6 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, 0.99
• PP5: Variant 9-34647097-C-A is Pathogenic according to our data. Variant chr9-34647097-C-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 25122.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GALT	NM_000155.4	c.91C>A	p.His31Asn	missense_variant	Exon 2 of 11	ENST00000378842.8	NP_000146.2
GALT	NM_001258332.2	c.-112C>A		5_prime_UTR_variant	Exon 2 of 9		NP_001245261.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GALT	ENST00000378842.8	c.91C>A	p.His31Asn	missense_variant	Exon 2 of 11	1	NM_000155.4	ENSP00000368119.4
ENSG00000258728	ENST00000556278.1	c.91C>A	p.His31Asn	missense_variant	Exon 2 of 8	5		ENSP00000451792.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

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

May 23, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. 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. ClinVar contains an entry for this variant (Variation ID: 25122). This missense change has been observed in individual(s) with classic galactosemia (PMID: 22944367). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces histidine, which is basic and polar, with asparagine, which is neutral and polar, at codon 31 of the GALT protein (p.His31Asn).

not specified Uncertain:1

Jul 25, 2025

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.91C>A (p.His31Asn) results in a conservative amino acid change in the encoded protein sequence. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change. The variant was absent in 251342 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.91C>A has been observed in at least one individual affected with Galactosemia (e.g. Boutron_2012). These data do not allow any conclusion about variant significance. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publication has been ascertained in the context of this evaluation (PMID: 22944367). ClinVar contains an entry for this variant (Variation ID: 25122). Based on the evidence outlined above, the variant was classified as uncertain significance.

Galactosemia Uncertain:1

Sep 28, 2020

Natera, Inc.

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: clinical testing

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.83
BayesDel_addAF	Pathogenic	0.40	D
BayesDel_noAF	Pathogenic	0.33
CADD	Pathogenic	29
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.95	D;.
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.90
LIST_S2	Pathogenic	0.99	D;D
M_CAP	Pathogenic	0.54	D
MetaRNN	Pathogenic	0.99	D;D
MetaSVM	Pathogenic	0.99	D
MutationAssessor	Pathogenic	3.9	H;.
PhyloP100		7.3
PrimateAI	Pathogenic	0.82	D
PROVEAN	Pathogenic	-6.2	D;D
Sift	Pathogenic	0.0	D;D
Sift4G	Pathogenic	0.0	D;D
Vest4		0.97
ClinPred		1.0	D
GERP RS		4.8
PromoterAI		-0.031	Neutral
Varity_R		0.98
gMVP		0.95
Mutation Taster		=15/85	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs111033643; hg19: chr9-34647094;