chr3-49723066-G-A

Variant names:

• chr3-49723066-G-A
• rs875989851
• NM_021971.4:c.308C>T

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM2 PP3_Moderate PP5_Moderate

The NM_021971.4(GMPPB):​c.308C>T​(p.Pro103Leu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. P103H) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 33)
• Consequence: GMPPB NM_021971.4 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:2
• Conservation: PhyloP100: 9.76
• Publications: 6 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: Labcorp Genetics (formerly Invitae), G2P, Ambry Genetics
• 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: Ambry Genetics, Orphanet, Labcorp Genetics (formerly Invitae)
• 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_pathogenic. The variant received 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.865
• PP5: Variant 3-49723066-G-A is Pathogenic according to our data. Variant chr3-49723066-G-A is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 225927.Status of the report is criteria_provided_single_submitter, 1 stars.

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.308C>T	p.Pro103Leu	missense	Exon 4 of 9	NP_068806.2	Q9Y5P6-1
	GMPPB	NM_013334.4		c.308C>T	p.Pro103Leu	missense	Exon 4 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.308C>T	p.Pro103Leu	missense	Exon 4 of 9	ENSP00000311130.6	Q9Y5P6-1
	GMPPB	ENST00000495627.2	TSL:2	c.308C>T	p.Pro103Leu	missense	Exon 4 of 9	ENSP00000503768.1	A0A7I2YQI5
	GMPPB	ENST00000308375.10	TSL:2	c.308C>T	p.Pro103Leu	missense	Exon 4 of 8	ENSP00000309092.6	Q9Y5P6-2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

ClinVar submissions

Significance: Likely pathogenic

Revision: criteria provided, single submitter

Pathogenic	VUS	Benign	Condition
1	-	-	Abnormality of the musculature (1)
1	-	-	Autosomal recessive limb-girdle muscular dystrophy type 2T (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.32
BayesDel_addAF	Pathogenic	0.32	D
BayesDel_noAF	Pathogenic	0.22
CADD	Pathogenic	26
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.86	D
Eigen	Uncertain	0.33
Eigen_PC	Uncertain	0.44
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Pathogenic	0.98	D
M_CAP	Pathogenic	0.70	D
MetaRNN	Pathogenic	0.87	D
MetaSVM	Uncertain	0.62	D
MutationAssessor	Uncertain	2.6	M
PhyloP100		9.8
PrimateAI	Uncertain	0.72	T
PROVEAN	Pathogenic	-9.1	D
REVEL	Pathogenic	0.74
Sift	Uncertain	0.024	D
Sift4G	Benign	0.11	T
Polyphen		0.015	B
Vest4		0.93
MutPred		0.62		Gain of sheet (P = 0.0477)
MVP		0.94
MPC		1.4
ClinPred		1.0	D
GERP RS		4.9
Varity_R		0.74
gMVP		0.72
Mutation Taster		=1/99	disease causing (ClinVar)

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: rs875989851; hg19: chr3-49760499;