1-43349267-G-C

Variant names:

• chr1-43349267-G-C
• rs121913613
• NM_005373.3:c.1473G>C

Variant summary

Our verdict is Uncertain significance. The variant received 3 ACMG points: 3P and 0B. PM2 PP2

The NM_005373.3(MPL):​c.1473G>C​(p.Trp491Cys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: MPL NM_005373.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.41
• Publications: 4 publications found

Genes affected

MPL (HGNC:7217): (MPL proto-oncogene, thrombopoietin receptor) In 1990 an oncogene, v-mpl, was identified from the murine myeloproliferative leukemia virus that was capable of immortalizing bone marrow hematopoietic cells from different lineages. In 1992 the human homologue, named, c-mpl, was cloned. Sequence data revealed that c-mpl encoded a protein that was homologous with members of the hematopoietic receptor superfamily. Presence of anti-sense oligodeoxynucleotides of c-mpl inhibited megakaryocyte colony formation. The ligand for c-mpl, thrombopoietin, was cloned in 1994. Thrombopoietin was shown to be the major regulator of megakaryocytopoiesis and platelet formation. The protein encoded by the c-mpl gene, CD110, is a 635 amino acid transmembrane domain, with two extracellular cytokine receptor domains and two intracellular cytokine receptor box motifs . TPO-R deficient mice were severely thrombocytopenic, emphasizing the important role of CD110 and thrombopoietin in megakaryocyte and platelet formation. Upon binding of thrombopoietin CD110 is dimerized and the JAK family of non-receptor tyrosine kinases, as well as the STAT family, the MAPK family, the adaptor protein Shc and the receptors themselves become tyrosine phosphorylated. [provided by RefSeq, Jul 2008]

MPL Gene-Disease associations (from GenCC):

• thrombocythemia 2

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Genomics England PanelApp, Labcorp Genetics (formerly Invitae), Ambry Genetics, ClinGen
• congenital amegakaryocytic thrombocytopenia

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Orphanet, Ambry Genetics
• congenital amegakaryocytic thrombocytopenia 1

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• familial thrombocytosis

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• hereditary isolated aplastic anemia

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 25 curated pathogenic missense variants (we use a threshold of 10). The gene has 7 curated benign missense variants. Gene score misZ: 0.39478 (below the threshold of 3.09). Trascript score misZ: 1.6963 (below the threshold of 3.09). GenCC associations: The gene is linked to hereditary isolated aplastic anemia, congenital amegakaryocytic thrombocytopenia, thrombocythemia 2, congenital amegakaryocytic thrombocytopenia 1, familial thrombocytosis.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MPL	NM_005373.3	c.1473G>C	p.Trp491Cys	missense_variant	Exon 10 of 12	ENST00000372470.9	NP_005364.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MPL	ENST00000372470.9	c.1473G>C	p.Trp491Cys	missense_variant	Exon 10 of 12	1	NM_005373.3	ENSP00000361548.3
MPL	ENST00000413998.7	c.1452G>C	p.Trp484Cys	missense_variant	Exon 10 of 12	1		ENSP00000414004.3
MPL	ENST00000638732.1	n.1473G>C		non_coding_transcript_exon_variant	Exon 10 of 10	1
MPL	ENST00000643351.1	c.3G>C	p.Trp1Cys	missense_variant	Exon 1 of 4			ENSP00000495154.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Essential thrombocythemia;C1327915:Congenital amegakaryocytic thrombocytopenia Uncertain:1

May 29, 2018

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). This variant has not been reported in the literature in individuals with MPL-related disease. This variant is not present in population databases (ExAC no frequency). This sequence change replaces tryptophan with cysteine at codon 491 of the MPL protein (p.Trp491Cys). The tryptophan residue is weakly conserved and there is a large physicochemical difference between tryptophan and cysteine.

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.75
BayesDel_addAF	Pathogenic	0.20	D
BayesDel_noAF	Uncertain	0.050
CADD	Pathogenic	29
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.89	D;.
Eigen	Uncertain	0.47
Eigen_PC	Uncertain	0.43
FATHMM_MKL	Uncertain	0.79	D
LIST_S2	Uncertain	0.86	D;D
M_CAP	Pathogenic	0.56	D
MetaRNN	Uncertain	0.69	D;D
MetaSVM	Uncertain	-0.093	T
MutationAssessor	Uncertain	2.0	M;.
PhyloP100		3.4
PrimateAI	Uncertain	0.78	T
PROVEAN	Uncertain	-4.1	D;.
REVEL	Uncertain	0.47
Sift	Uncertain	0.012	D;.
Sift4G	Pathogenic	0.0	D;.
Vest4		0.70
ClinPred		0.96	D
GERP RS		4.5
PromoterAI		-0.14	Neutral
Varity_R		0.37
gMVP		0.60
Mutation Taster		=63/37	polymorphism

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

Other links and lift over

dbSNP: rs121913613; hg19: chr1-43814938;