NM_005373.3(MPL):c.79+2T>A AND Congenital amegakaryocytic thrombocytopenia

Germline classification:: Pathogenic/Likely pathogenic (5 submissions)
Last evaluated:: Dec 20, 2019
Review status:: 2 stars out of maximum of 4 stars
criteria provided, multiple submitters, no conflicts

Somatic classification of clinical impact:: None
Review status:: (0/4) 0 stars out of maximum of 4 stars
no assertion criteria provided

Somatic classification of oncogenicity:: None
Review status:: (0/4) 0 stars out of maximum of 4 stars
no assertion criteria provided

Record status:: current
Accession:: RCV000586535.13

Allele description [Variation Report for NM_005373.3(MPL):c.79+2T>A]

NM_005373.3(MPL):c.79+2T>A

Gene:

MPL:MPL proto-oncogene, thrombopoietin receptor [Gene - OMIM - HGNC]

Variant type:

single nucleotide variant

Cytogenetic location:

1p34.2

Genomic location:

Preferred name:

NM_005373.3(MPL):c.79+2T>A

HGVS:

NC_000001.11:g.43337929T>A
NG_007525.1:g.5126T>A
NM_005373.3:c.79+2T>AMANE SELECT
LRG_510t1:c.79+2T>A
LRG_510:g.5126T>A
NC_000001.10:g.43803600T>A
NM_005373.2:c.79+2T>A
c.79+2T>A (p.?)

Links:

dbSNP: rs146249964

NCBI 1000 Genomes Browser:

rs146249964

Molecular consequence:

NM_005373.3:c.79+2T>A - splice donor variant - [Sequence Ontology: SO:0001575]

Observations:

Condition(s)

Name:: Congenital amegakaryocytic thrombocytopenia
Identifiers:: MONDO: MONDO:0800451; MedGen: C1327915; Orphanet: 3319; OMIM: PS604498

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Submission Accession	Submitter	Review Status (Assertion method)	Clinical Significance (Last evaluated)	Origin	Method	Citations
SCV000698586	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	criteria provided, single submitter (LabCorp Variant Classification Summary - May 2015)	Pathogenic (Oct 24, 2016)	germline	clinical testing	PubMed (1) [See all records that cite this PMID] LabCorp Variant Classification Summary - May 2015.docx, Citation Link,
SCV000712164	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	criteria provided, single submitter (LMM Criteria)	Likely pathogenic (Feb 28, 2017)	germline	clinical testing	PubMed (4) [See all records that cite these PMIDs] 21489838, 16470591, 24728327, 24033266
SCV001142298	Reproductive Health Research and Development, BGI Genomics	no assertion criteria provided	Pathogenic (Jan 6, 2020)	germline	curation
SCV001162889	Baylor Genetics	criteria provided, single submitter (ACMG Guidelines, 2015)	Pathogenic	germline	clinical testing	PubMed (1) [See all records that cite this PMID]
SCV001194134	Myriad Genetics, Inc.	criteria provided, single submitter (Myriad Women's Health Autosomal Recessive and X-Linked Classification Criteria (2019))	Pathogenic (Dec 20, 2019)	unknown	clinical testing	PubMed (2) [See all records that cite these PMIDs] 21489838, 16470591 Citation Link

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Summary from all submissions

Ethnicity	Origin	Affected	Individuals	Families	Chromosomes tested	Number Tested	Family history	Method
not provided	germline	not provided	1	1	not provided	not provided	not provided	clinical testing
not provided	unknown	unknown	not provided	not provided	not provided	not provided	not provided	clinical testing
not provided	germline	unknown	not provided	not provided	not provided	not provided	not provided	clinical testing, curation

Citations

PubMed

Germline variation in cancer-susceptibility genes in a healthy, ancestrally diverse cohort: implications for individual genome sequencing.

Bodian DL, McCutcheon JN, Kothiyal P, Huddleston KC, Iyer RK, Vockley JG, Niederhuber JE.

PLoS One. 2014;9(4):e94554. doi: 10.1371/journal.pone.0094554.

PubMed [citation]

PMID:: 24728327
PMCID:: PMC3984285

A systematic approach to assessing the clinical significance of genetic variants.

Duzkale H, Shen J, McLaughlin H, Alfares A, Kelly MA, Pugh TJ, Funke BH, Rehm HL, Lebo MS.

Clin Genet. 2013 Nov;84(5):453-63. doi: 10.1111/cge.12257.

PubMed [citation]

PMID:: 24033266
PMCID:: PMC3995020

See all PubMed Citations (5)

Details of each submission

From Women's Health and Genetics/Laboratory Corporation of America, LabCorp, SCV000698586.1

#	Ethnicity	Individuals	Chromosomes Tested	Family History	Method	Citations
1	not provided	not provided	not provided	not provided	clinical testing	PubMed (1)

Description

Variant summary: The MPL c.79+2T>A variant involves the alteration of a splice donor site in intron 1, which 5/5 splice prediction tools predict the removal this splice donor site, however, functional studies have yet to be performed to assess these predictions. This variant was found in 58/100444 control chromosomes at a frequency of 0.0005774, which does not exceed the estimated maximal expected allele frequency of a pathogenic MPL variant (0.002357). This variant has been reported in two patients with Amegakaryocytic Thrombocytopenia in homozygous state (Germeshausen_2006 and Jalas_2011). It has also been reported as germline variant in patients with Breast Cancer, Non-Small Cell Lung Cancer, Melanoma and Non-Seminomatous Germ Cell Tumor (Schrader_2016). The variant is a founder mutation in Ashkenazi Jewish population with a carrier frequency of 1 in 75 (Jalas_2011). One clinical diagnostic laboratory in ClinVar classified this variant as pathogenic. Taken together, this variant is classified as Pathogenic.

#	Sample				Method		Observation
#	Origin	Affected	Number tested	Tissue	Purpose	Method	Individuals	Allele frequency	Families	Co-occurrences
1	germline	unknown	not provided	not provided	not provided		not provided	not provided	not provided	not provided

From Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine, SCV000712164.1

#	Ethnicity	Individuals	Chromosomes Tested	Family History	Method	Citations
1	not provided	1	not provided	not provided	clinical testing	PubMed (4)

Description

The c.79+2T>A variant in MPL has been reported in the homozygous state in 2 indi viduals with congenital amegakaryocyctic thrombocytopenia (CAMT; Germeshausen 20 06, Jalas 2011). It has also been identified in 0.8% (80/9916) of Ashkenazi Jewi sh chromosomes by the Genome Aggregation Database (gnomAD, http://gnomad.broadin stitute.org/; dbSNP rs146249964), and is suggested to be a founder variant in th e Ashkenazi Jewish population (Jalas 2011). This variant occurs in the invariant region (+/- 1,2) of the splice consensus sequence and is predicted to cause alt ered splicing leading to an abnormal or absent protein. Loss of function of the MPL gene is an established mechanism of disease. In summary, although additional studies are required to fully establish its clinical significance, the c.79+2T> A variant is likely pathogenic.

#	Sample				Method		Observation
#	Origin	Affected	Number tested	Tissue	Purpose	Method	Individuals	Allele frequency	Families	Co-occurrences
1	germline	not provided	not provided	not provided	not provided		1	not provided	1	not provided

From Reproductive Health Research and Development, BGI Genomics, SCV001142298.1

#	Ethnicity	Individuals	Chromosomes Tested	Family History	Method	Citations
1	not provided	not provided	not provided	not provided	curation	not provided

Description

NG_007525.1(NM_005373.2):c.79+2T>A in the MPL gene has an allele frequency of 0.008 in Ashkenazi Jewish subpopulation in the gnomAD database. This variant is located on a biological transcript and leads to exon skipping or use of a cryptic splice site disrupts reading frame and is therefore predicted to undergo NMD. It has been reported as a founder mutation the Ashkenazi Jewish population (PMID: 21489838). This variant has been reported in homozygous state in two patients with Amegakaryocytic Thrombocytopenia (PMID: 16470591; 21489838). Taken together, we interprete this variant as Pathogenic/Likely pathogenic variant. ACMG/AMP criteria applied: PVS1; PM3; PP4

#	Sample				Method		Observation
#	Origin	Affected	Number tested	Tissue	Purpose	Method	Individuals	Allele frequency	Families	Co-occurrences
1	germline	unknown	not provided	not provided	not provided		not provided	not provided	not provided	not provided

From Baylor Genetics, SCV001162889.1

#	Ethnicity	Individuals	Chromosomes Tested	Family History	Method	Citations
1	not provided	not provided	not provided	not provided	clinical testing	PubMed (1)

#	Sample				Method		Observation
#	Origin	Affected	Number tested	Tissue	Purpose	Method	Individuals	Allele frequency	Families	Co-occurrences
1	germline	unknown	not provided	not provided	not provided		not provided	not provided	not provided	not provided

From Myriad Genetics, Inc., SCV001194134.2

#	Ethnicity	Individuals	Chromosomes Tested	Family History	Method	Citations
1	not provided	not provided	not provided	not provided	clinical testing	PubMed (2)

Description

NM_005373.2(MPL):c.79+2T>A is classified as pathogenic in the context of congenital amegakaryocytic thrombocytopenia. Sources cited for classification include the following: PMID 21489838 and 16470591. Classification of NM_005373.2(MPL):c.79+2T>A is based on the following criteria: The variant is located at a canonical splice site, is expected to disrupt gene function and is reported in individuals with the relevant phenotype. Please note: this variant was assessed in the context of healthy population screening.

#	Sample				Method		Observation
#	Origin	Affected	Number tested	Tissue	Purpose	Method	Individuals	Allele frequency	Families	Co-occurrences
1	unknown	unknown	not provided	not provided	not provided		not provided	not provided	not provided	not provided

Last Updated: Jul 23, 2024

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