NM_003774.5:c.1253G>C

Variant names:

• chr12-89523297-C-G
• rs530075677
• NM_003774.5:c.1253G>C

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM2

The NM_003774.5(GALNT4):​c.1253G>C​(p.Arg418Pro) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000205 in 1,461,700 control chromosomes in the GnomAD database, with no homozygous occurrence. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R418Q) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: GALNT4 NM_003774.5 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 2.06
• Publications: 0 publications found

Genes affected

GALNT4 (HGNC:4126): (polypeptide N-acetylgalactosaminyltransferase 4) This gene encodes a member of the UDP-N-acetyl-alpha-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase (GalNAc-T) family of enzymes. GalNAc-Ts initiate mucin-type O-linked glycosylation in the Golgi apparatus by catalyzing the transfer of GalNAc to serine and threonine residues on target proteins. They are characterized by an N-terminal transmembrane domain, a stem region, a lumenal catalytic domain containing a GT1 motif and Gal/GalNAc transferase motif, and a C-terminal ricin/lectin-like domain. GalNAc-Ts have different, but overlapping, substrate specificities and patterns of expression. In vitro, the encoded protein can complement other GalNAc-Ts in the complete O-glycosylation of the mucin-1 tandem repeat and can O-glycosylate the P-selectin glycoprotein ligand-1 molecule. The coding region of this gene is contained within a single exon. Fusion transcripts, which combine part of this gene with the 5' exons of the neighboring POC1B (POC1 centriolar protein homolog B) gene, also exist. [provided by RefSeq, Dec 2010]

POC1B-GALNT4 (HGNC:42957): (POC1B-GALNT4 readthrough) This locus represents naturally occurring transcripts that splice the 5' exons of the POC1B (POC1 centriolar protein homolog B) gene on chromosome 12 to the GALNT4 (UDP-N-acetyl-alpha-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase 4) gene, which is located within a POC1B intron. Alternative splicing results in two transcript variants, one of which encodes a fusion isoform that shares sequence identity with the products of each individual gene. [provided by RefSeq, Dec 2010]

POC1B (HGNC:30836): (POC1 centriolar protein B) POC1 proteins contain an N-terminal WD40 domain and a C-terminal coiled coil domain and are part of centrosomes. They play an important role in basal body and cilia formation. This gene encodes one of the two POC1 proteins found in humans. Mutation in this gene result in autosomal-recessive cone-rod dystrophy. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Oct 2014]

POC1B Gene-Disease associations (from GenCC):

• cone-rod dystrophy 20

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: G2P, ClinGen, Labcorp Genetics (formerly Invitae)
• ciliopathy

  Inheritance: AR Classification: MODERATE Submitted by: Ambry Genetics
• cone-rod dystrophy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

POC1B-DUSP6 (HGNC:):

ACMG classification

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_003774.5. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GALNT4	NM_003774.5	MANE Select	c.1253G>C	p.Arg418Pro	missense	Exon 1 of 1	NP_003765.2
	POC1B	NM_172240.3	MANE Select	c.100+1823G>C		intron	N/A	NP_758440.1	Q8TC44-1
	POC1B-GALNT4	NM_001199781.2		c.1244G>C	p.Arg415Pro	missense	Exon 3 of 3	NP_001186710.1	F8VUJ3

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GALNT4	ENST00000529983.3	TSL:6 MANE Select	c.1253G>C	p.Arg418Pro	missense	Exon 1 of 1	ENSP00000436604.2	Q8N4A0-1
	POC1B-GALNT4	ENST00000548729.5	TSL:2	c.1244G>C	p.Arg415Pro	missense	Exon 3 of 3	ENSP00000447852.1	F8VUJ3
	POC1B	ENST00000313546.8	TSL:1 MANE Select	c.100+1823G>C		intron	N/A	ENSP00000323302.3	Q8TC44-1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461700 Hom.: 0 Cov.: 85 AF XY: 0.00000275 AC XY: 2 AN XY: 727128

African (AFR) AF: 0.0000299 AC: 1 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: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53390

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00000180 AC: 2 AN: 1111870

Other (OTH) AF: 0.00 AC: 0 AN: 60374

GnomAD4 genome Cov.: 33

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.87
BayesDel_addAF	Uncertain	0.040	T
BayesDel_noAF	Benign	-0.18
CADD	Benign	21
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.59	D
Eigen	Uncertain	0.31
Eigen_PC	Benign	0.21
FATHMM_MKL	Uncertain	0.84	D
LIST_S2	Uncertain	0.97	D
M_CAP	Benign	0.042	D
MetaRNN	Uncertain	0.57	D
MetaSVM	Benign	-0.47	T
MutationAssessor	Pathogenic	3.1	M
PhyloP100		2.1
PrimateAI	Uncertain	0.53	T
PROVEAN	Uncertain	-4.0	D
REVEL	Benign	0.24
Sift	Uncertain	0.0080	D
Sift4G	Uncertain	0.045	D
Polyphen		0.60	P
Vest4		0.56
MutPred		0.60		Loss of MoRF binding (P = 0.0064)
MVP		0.52
MPC		0.46
ClinPred		0.96	D
GERP RS		5.0
Varity_R		0.86
gMVP		0.93
Mutation Taster		=48/52	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: rs530075677; hg19: chr12-89917074;