9-34649064-A-G

Variant names:

• chr9-34649064-A-G
• rs775789069
• NM_000155.4:c.887A>G

Variant summary

Our verdict is Likely pathogenic. The variant received 9 ACMG points: 9P and 0B. PM1 PM2 PP2 PP3_Strong

The NM_000155.4(GALT):​c.887A>G​(p.Tyr296Cys) variant causes a missense change. The variant allele was found at a frequency of 0.000000684 in 1,461,800 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 Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: GALT NM_000155.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 6.42
• Publications: 1 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: Likely_pathogenic. The variant received 9 ACMG points.

• PM1: In a hotspot region, there are 11 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, 0.993

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000155.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GALT	NM_000155.4	MANE Select	c.887A>G	p.Tyr296Cys	missense	Exon 9 of 11	NP_000146.2
	GALT	NM_001258332.2		c.560A>G	p.Tyr187Cys	missense	Exon 7 of 9	NP_001245261.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GALT	ENST00000378842.8	TSL:1 MANE Select	c.887A>G	p.Tyr296Cys	missense	Exon 9 of 11	ENSP00000368119.4
	ENSG00000258728	ENST00000556278.1	TSL:5	c.432+608A>G		intron	N/A	ENSP00000451792.1
	GALT	ENST00000450095.6	TSL:2	c.560A>G	p.Tyr187Cys	missense	Exon 7 of 9	ENSP00000401956.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.00000398 AC: 1 AN: 251494 AF XY: 0.00

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 FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000879

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461800 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 727202

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39698

South Asian (SAS) AF: 0.00 AC: 0 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53418

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111932

Other (OTH) AF: 0.00 AC: 0 AN: 60390

GnomAD4 genome Cov.: 32

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

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

Apr 28, 2018

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). This variant has not been reported in the literature in individuals with GALT-related disease. This variant is present in population databases (rs775789069, ExAC 0.001%). This sequence change replaces tyrosine with cysteine at codon 296 of the GALT protein (p.Tyr296Cys). The tyrosine residue is highly conserved and there is a large physicochemical difference between tyrosine and cysteine.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.74
BayesDel_addAF	Pathogenic	0.58	D
BayesDel_noAF	Pathogenic	0.59
CADD	Pathogenic	26
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.99	D
Eigen	Pathogenic	0.99
Eigen_PC	Pathogenic	0.90
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Pathogenic	1.0	D
M_CAP	Pathogenic	0.66	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	0.96	D
MutationAssessor	Pathogenic	4.4	H
PhyloP100		6.4
PrimateAI	Uncertain	0.77	T
PROVEAN	Pathogenic	-8.8	D
REVEL	Pathogenic	0.99
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.93
MutPred		0.98		Loss of disorder (P = 0.1273)
MVP		1.0
MPC		2.1
ClinPred		1.0	D
GERP RS		5.7
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.99
gMVP		0.99
Mutation Taster		=3/97	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		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: rs775789069; hg19: chr9-34649061; COSMIC: COSV58841147; COSMIC: COSV58841147;