NM_000355.4:c.921A>C

Variant names:

• chr22-30615768-A-C
• rs138738105
• NM_000355.4:c.921A>C

Variant summary

Our verdict is Benign. The variant received -10 ACMG points: 0P and 10B. BP4_Strong BP6 BP7 BS1

The NM_000355.4(TCN2):​c.921A>C​(p.Pro307Pro) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000294 in 1,614,210 control chromosomes in the GnomAD database, including 1 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: 𝑓 0.00016 (0 hom., cov: 33)
  • Exomes 𝑓: 0.00031 (1 hom.)
• Consequence: TCN2 NM_000355.4 synonymous
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1 B:5
• Conservation: PhyloP100: 1.39
• Publications: 1 publications found

Genes affected

TCN2 (HGNC:11653): (transcobalamin 2) This gene encodes a member of the vitamin B12-binding protein family. This family of proteins, alternatively referred to as R binders, is expressed in various tissues and secretions. This plasma protein binds cobalamin and mediates the transport of cobalamin into cells. This protein and other mammalian cobalamin-binding proteins, such as transcobalamin I and gastric intrisic factor, may have evolved by duplication of a common ancestral gene. Alternative splicing results in multiple transcript variants.[provided by RefSeq, May 2010]

TCN2 Gene-Disease associations (from GenCC):

• transcobalamin II deficiency

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Ambry Genetics, Labcorp Genetics (formerly Invitae), Orphanet

ACMG classification

Our verdict: Benign. The variant received -10 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.61).
• BP6: Variant 22-30615768-A-C is Benign according to our data. Variant chr22-30615768-A-C is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 341206.
• BP7: Synonymous conserved (PhyloP=1.39 with no splicing effect.
• BS1: Variant frequency is greater than expected in population sas. GnomAd4 allele frequency = 0.000164 (25/152322) while in subpopulation SAS AF = 0.00207 (10/4832). AF 95% confidence interval is 0.00112. There are 0 homozygotes in GnomAd4. There are 17 alleles in the male GnomAd4 subpopulation. Median coverage is 33. This position passed quality control check.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000355.4. 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
	TCN2	NM_000355.4	MANE Select	c.921A>C	p.Pro307Pro	synonymous	Exon 6 of 9	NP_000346.2
	TCN2	NM_001184726.2		c.840A>C	p.Pro280Pro	synonymous	Exon 6 of 9	NP_001171655.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TCN2	ENST00000215838.8	TSL:1 MANE Select	c.921A>C	p.Pro307Pro	synonymous	Exon 6 of 9	ENSP00000215838.3
	TCN2	ENST00000407817.3	TSL:1	c.840A>C	p.Pro280Pro	synonymous	Exon 6 of 9	ENSP00000384914.3
	TCN2	ENST00000698271.1		c.951A>C	p.Pro317Pro	synonymous	Exon 6 of 9	ENSP00000513642.1

Frequencies

GnomAD3 genomes AF: 0.000164 AC: 25 AN: 152204 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000131

Gnomad ASJ AF: 0.000288

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00207

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.000162

Gnomad OTH AF: 0.000478

GnomAD2 exomes AF: 0.000354 AC: 89 AN: 251470 AF XY: 0.000441

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.000231

Gnomad ASJ exome AF: 0.0000992

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.000255

Gnomad OTH exome AF: 0.000489

GnomAD4 exome AF: 0.000307 AC: 449 AN: 1461888 Hom.: 1 Cov.: 35 AF XY: 0.000380 AC XY: 276 AN XY: 727244

African (AFR) AF: 0.0000299 AC: 1 AN: 33480

American (AMR) AF: 0.000246 AC: 11 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.000191 AC: 5 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00212 AC: 183 AN: 86258

European-Finnish (FIN) AF: 0.0000187 AC: 1 AN: 53418

Middle Eastern (MID) AF: 0.00225 AC: 13 AN: 5768

European-Non Finnish (NFE) AF: 0.000186 AC: 207 AN: 1112008

Other (OTH) AF: 0.000464 AC: 28 AN: 60396

GnomAD4 genome AF: 0.000164 AC: 25 AN: 152322 Hom.: 0 Cov.: 33 AF XY: 0.000228 AC XY: 17 AN XY: 74486

African (AFR) AF: 0.00 AC: 0 AN: 41574

American (AMR) AF: 0.000131 AC: 2 AN: 15294

Ashkenazi Jewish (ASJ) AF: 0.000288 AC: 1 AN: 3472

East Asian (EAS) AF: 0.00 AC: 0 AN: 5180

South Asian (SAS) AF: 0.00207 AC: 10 AN: 4832

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10624

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 294

European-Non Finnish (NFE) AF: 0.000162 AC: 11 AN: 68024

Other (OTH) AF: 0.000473 AC: 1 AN: 2116

Alfa AF: 0.000223 Hom.: 0

Bravo AF: 0.000117

Asia WGS AF: 0.000289 AC: 1 AN: 3478

EpiCase AF: 0.000109

EpiControl AF: 0.000356

ClinVar

ClinVar submissions as Germline

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

Pathogenic	VUS	Benign	Condition
-	-	4	not provided (4)
-	1	1	Transcobalamin II deficiency (2)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.61
CADD	Benign	8.5
DANN	Benign	0.71
PhyloP100		1.4
Mutation Taster		=100/0	polymorphism

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: rs138738105; hg19: chr22-31011755;