rs28928908

Positions:

• chr1-43340096-C-A
• chr1-43340096-C-T

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2 PP3_Strong

The NM_005373.3(MPL):​c.823C>A​(p.Pro275Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,798 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: MPL NM_005373.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter P:1 U:2
• Conservation: PhyloP100: 3.00

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 (HGNC:):

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.974

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
MPL	NM_005373.3	c.823C>A	p.Pro275Thr	missense_variant	5/12	ENST00000372470.9	NP_005364.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
MPL	ENST00000372470.9	c.823C>A	p.Pro275Thr	missense_variant	5/12	1	NM_005373.3	ENSP00000361548.3
MPL	ENST00000413998.7	c.802C>A	p.Pro268Thr	missense_variant	5/12	1		ENSP00000414004.3
MPL	ENST00000638732.1	n.823C>A		non_coding_transcript_exon_variant	5/10	1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251032 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135710

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000881

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461798 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 727200

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Pathogenic:1 Uncertain:2

Revision: criteria provided, single submitter

Submissions by phenotype

Congenital amegakaryocytic thrombocytopenia 1 Pathogenic:1

Pathogenic, no assertion criteria provided

literature only

OMIM

Jan 01, 2001

- -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Jun 02, 2023

Variant summary: MPL c.823C>A (p.Pro275Thr) results in a non-conservative amino acid change located in the Fibronectin type III domain (IPR003961) of the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 4e-06 in 251032 control chromosomes. c.823C>A has been reported in the literature in at-least one compound heterozygous individual affected with Congenital Amegakaryocytic Thrombocytopenia (example, Ballmaier_2001). To our knowledge, no variant specific experimental evidence demonstrating an impact on protein function has been reported. The following publications have been ascertained in the context of this evaluation (PMID: 11133753, 24438083). No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014. Based on the evidence outlined above, the variant was classified as uncertain significance. -

Congenital amegakaryocytic thrombocytopenia Uncertain:1

Uncertain significance, no assertion criteria provided

clinical testing

Zotz-Klimas Genetics Lab, MVZ Zotz Klimas

Oct 30, 2023

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.23
BayesDel_addAF	Pathogenic	0.32	D
BayesDel_noAF	Pathogenic	0.22
CADD	Uncertain	23
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.84	D;.
Eigen	Pathogenic	0.72
Eigen_PC	Pathogenic	0.69
FATHMM_MKL	Uncertain	0.92	D
LIST_S2	Benign	0.81	T;T
M_CAP	Uncertain	0.090	D
MetaRNN	Pathogenic	0.97	D;D
MetaSVM	Uncertain	0.65	D
MutationAssessor	Uncertain	2.3	M;.
PrimateAI	Benign	0.41	T
PROVEAN	Pathogenic	-4.9	D;.
REVEL	Pathogenic	0.69
Sift	Uncertain	0.0080	D;.
Sift4G	Uncertain	0.047	D;.
Polyphen		1.0	D;.
Vest4		0.37
MutPred		0.92		Loss of catalytic residue at P275 (P = 0.1933);.;
MVP		0.93
MPC		0.79
ClinPred		0.98	D
GERP RS		6.0
Varity_R		0.41
gMVP		0.34

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

Publications

LitVar

Other links and lift over

dbSNP: rs28928908; hg19: chr1-43805767;