chr1-161174036-G-A

Variant names:

• chr1-161174036-G-A
• rs1662487514
• NM_003779.4:c.503C>T

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

The NM_003779.4(B4GALT3):​c.503C>T​(p.Thr168Ile) variant causes a missense change. The variant allele was found at a frequency of 0.00000411 in 1,461,446 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000041 (0 hom.)
• Consequence: B4GALT3 NM_003779.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 6.91

Genes affected

B4GALT3 (HGNC:926): (beta-1,4-galactosyltransferase 3) This gene is one of seven beta-1,4-galactosyltransferase (beta4GalT) genes. They encode type II membrane-bound glycoproteins that appear to have exclusive specificity for the donor substrate UDP-galactose; all transfer galactose in a beta1,4 linkage to similar acceptor sugars: GlcNAc, Glc, and Xyl. Each beta4GalT has a distinct function in the biosynthesis of different glycoconjugates and saccharide structures. As type II membrane proteins, they have an N-terminal hydrophobic signal sequence that directs the protein to the Golgi apparatus and which then remains uncleaved to function as a transmembrane anchor. By sequence similarity, the beta4GalTs form four groups: beta4GalT1 and beta4GalT2, beta4GalT3 and beta4GalT4, beta4GalT5 and beta4GalT6, and beta4GalT7. This gene encodes an enzyme that may be mainly involved in the synthesis of the first N-acetyllactosamine unit of poly-N-acetyllactosamine chains. Multiple alternatively spliced transcript variants encoding the same protein have been found for this gene. [provided by RefSeq, Dec 2010]

PPOX (HGNC:9280): (protoporphyrinogen oxidase) This gene encodes the penultimate enzyme of heme biosynthesis, which catalyzes the 6-electron oxidation of protoporphyrinogen IX to form protoporphyrin IX. Mutations in this gene cause variegate porphyria, an autosomal dominant disorder of heme metabolism resulting from a deficiency in protoporphyrinogen oxidase, an enzyme located on the inner mitochondrial membrane. Alternatively spliced transcript variants encoding the same protein have been identified. [provided by RefSeq, Jul 2008]

ACMG classification

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 rank	MANE	Protein	UniProt
B4GALT3	NM_003779.4	c.503C>T	p.Thr168Ile	missense_variant	Exon 5 of 8	ENST00000319769.10	NP_003770.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
B4GALT3	ENST00000319769.10	c.503C>T	p.Thr168Ile	missense_variant	Exon 5 of 8	1	NM_003779.4	ENSP00000320965.5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000411 AC: 6 AN: 1461446 Hom.: 0 Cov.: 32 AF XY: 0.00000550 AC XY: 4 AN XY: 727030

Gnomad4 AFR exome AF: 0.00

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: 0.00000180

Gnomad4 OTH exome AF: 0.0000662

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

May 01, 2024

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.503C>T (p.T168I) alteration is located in exon 5 (coding exon 3) of the B4GALT3 gene. This alteration results from a C to T substitution at nucleotide position 503, causing the threonine (T) at amino acid position 168 to be replaced by an isoleucine (I). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.72
BayesDel_addAF	Benign	-0.0041	T
BayesDel_noAF	Benign	-0.24
CADD	Pathogenic	30
DANN	Uncertain	1.0
DEOGEN2	Benign	0.15	T;T;T
Eigen	Uncertain	0.33
Eigen_PC	Uncertain	0.39
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.86	.;D;.
M_CAP	Benign	0.012	T
MetaRNN	Uncertain	0.69	D;D;D
MetaSVM	Benign	-0.96	T
MutationAssessor	Benign	1.7	L;L;L
PrimateAI	Uncertain	0.73	T
PROVEAN	Uncertain	-4.1	D;.;D
REVEL	Benign	0.22
Sift	Benign	0.071	T;.;T
Sift4G	Benign	0.072	T;T;T
Polyphen		0.59	P;P;P
Vest4		0.59
MutPred		0.49		Loss of methylation at R171 (P = 0.1073);Loss of methylation at R171 (P = 0.1073);Loss of methylation at R171 (P = 0.1073);
MVP		0.63
MPC		0.63
ClinPred		0.99	D
GERP RS		4.3
Varity_R		0.32
gMVP		0.67

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.27		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.27		Position offset: -10

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

Publications

LitVar

Other links and lift over

dbSNP: rs1662487514; hg19: chr1-161143826;