NM_000155.4:c.554C>G

Variant names:

• chr9-34648161-C-G
• rs111033722
• NM_000155.4:c.554C>G

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PM1 PM2 PM5 PP3_Strong

The NM_000155.4(GALT):​c.554C>G​(p.Pro185Arg) variant causes a missense change. 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 Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. P185H) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: GALT NM_000155.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 6.63

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 10 ACMG points.

• PM1: In a strand (size 10) in uniprot entity GALT_HUMAN there are 4 pathogenic changes around while only 0 benign (100%) 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 chrnull-null-null-null is described in UniProt as null.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.992

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GALT	NM_000155.4	c.554C>G	p.Pro185Arg	missense_variant	Exon 6 of 11	ENST00000378842.8	NP_000146.2
GALT	NM_001258332.2	c.227C>G	p.Pro76Arg	missense_variant	Exon 4 of 9		NP_001245261.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GALT	ENST00000378842.8	c.554C>G	p.Pro185Arg	missense_variant	Exon 6 of 11	1	NM_000155.4	ENSP00000368119.4
ENSG00000258728	ENST00000556278.1	c.299C>G	p.Pro100Arg	missense_variant	Exon 3 of 8	5		ENSP00000451792.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Mar 26, 2024

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.554C>G (p.Pro185Arg) results in a non-conservative amino acid change located in the Galactose-1-phosphate uridyl transferase, N-terminal domain (IPR005849) of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 251476 control chromosomes (gnomAD). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. To our knowledge, no occurrence of c.554C>G in individuals affected with Galactosemia has been reported. At least one publication reports experimental evidence evaluating an impact on protein function, however, does not allow convincing conclusions about the variant effect (Quimby_1996). The following publication has been ascertained in the context of this evaluation (PMID: 8900165). No submitters have cited clinical-significance assessments for this variant to ClinVar. Based on the evidence outlined above, the variant was classified as uncertain significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.96
BayesDel_addAF	Pathogenic	0.57	D
BayesDel_noAF	Pathogenic	0.58
CADD	Pathogenic	33
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.98	.;D;.
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.90
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	1.0	D;D;D
M_CAP	Pathogenic	0.53	D
MetaRNN	Pathogenic	0.99	D;D;D
MetaSVM	Pathogenic	0.89	D
MutationAssessor	Pathogenic	3.9	.;H;.
PrimateAI	Uncertain	0.66	T
PROVEAN	Pathogenic	-9.0	D;D;D
REVEL	Pathogenic	0.97
Sift	Pathogenic	0.0	D;D;D
Sift4G	Pathogenic	0.0	D;D;D
Polyphen		1.0	.;D;.
Vest4		0.94
MutPred		0.96		.;Gain of MoRF binding (P = 0.0667);.;
MVP		1.0
MPC		1.9
ClinPred		1.0	D
GERP RS		4.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.99
gMVP		1.0

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.22		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.22		Position offset: -46

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

Publications

LitVar

Other links and lift over

dbSNP: rs111033722; hg19: chr9-34648158;