chr3-49722698-T-G

Variant names:

• chr3-49722698-T-G
• NM_021971.4:c.459A>C
• GMPPB p.Thr153Thr

Variant summary

Our verdict is Likely benign. The variant received -3 ACMG points: 2P and 5B. PM2 BP4_Strong BP7

The NM_021971.4(GMPPB):​c.459A>C​(p.Thr153Thr) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. T153T) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 33)
• Consequence: GMPPB NM_021971.4 synonymous
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: -0.00800
• Publications: 0 publications found

Genes affected

GMPPB (HGNC:22932): (GDP-mannose pyrophosphorylase B) This gene is thought to encode a GDP-mannose pyrophosphorylase. The encoded protein catalyzes the conversion of mannose-1-phosphate and GTP to GDP-mannose, a reaction involved in the production of N-linked oligosaccharides. Alternatively spliced transcript variants encoding distinct isoforms have been described. [provided by RefSeq, Jan 2009]

GMPPB Gene-Disease associations (from GenCC):

• muscular dystrophy-dystroglycanopathy (congenital with brain and eye anomalies), type A14

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: G2P, Ambry Genetics, Labcorp Genetics (formerly Invitae)
• myopathy caused by variation in GMPPB

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• autosomal recessive limb-girdle muscular dystrophy type 2T

  Inheritance: AR Classification: STRONG, MODERATE, SUPPORTIVE Submitted by: Orphanet, Labcorp Genetics (formerly Invitae), Ambry Genetics
• congenital myasthenic syndrome

  Inheritance: AR Classification: STRONG Submitted by: Genomics England PanelApp
• congenital muscular dystrophy with cerebellar involvement

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• congenital muscular dystrophy with intellectual disability

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• congenital myasthenic syndromes with glycosylation defect

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• muscle-eye-brain disease

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Likely_benign. The variant received -3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.62).
• BP7: Synonymous conserved (PhyloP=-0.008 with no splicing effect.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_021971.4. 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
	GMPPB	NM_021971.4	MANE Select	c.459A>C	p.Thr153Thr	synonymous	Exon 5 of 9	NP_068806.2	Q9Y5P6-1
	GMPPB	NM_013334.4		c.459A>C	p.Thr153Thr	synonymous	Exon 5 of 8	NP_037466.3

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GMPPB	ENST00000308388.7	TSL:1 MANE Select	c.459A>C	p.Thr153Thr	synonymous	Exon 5 of 9	ENSP00000311130.6	Q9Y5P6-1
	GMPPB	ENST00000495627.2	TSL:2	c.567A>C	p.Thr189Thr	synonymous	Exon 5 of 9	ENSP00000503768.1	A0A7I2YQI5
	GMPPB	ENST00000308375.10	TSL:2	c.459A>C	p.Thr153Thr	synonymous	Exon 5 of 8	ENSP00000309092.6	Q9Y5P6-2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 33

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.62
CADD	Benign	6.3
DANN	Benign	0.82
PhyloP100		-0.0080

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

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

MaxEntScan Visualizer can be used to analyze the impact of this mutation on the neighboring sequence.

Other links and lift over

hg19: chr3-49760131;