This test analyzes the MPL gene, which is associated with congenital amegakaryocytic thrombocytopenia (CAMT). CAMT is an infantile onset condition that is characterized by bone marrow failure and low numbers of megakaryocytes and platelets. Certain variants cause CAMTII, which is a milder form of disease.
Genetic testing of these genes may confirm a diagnosis and help guide treatment and management decisions. Identification of a disease-causing variant would also guide testing and diagnosis of at-risk relatives. This test is specifically designed for heritable germline mutations and is not appropriate for the detection of somatic mutations in tumor tissue.
These genes can also be ordered as part of a broader panel. Depending on the individual’s clinical and family history, this panel may be appropriate and can be ordered at no additional charge.
Congenital amegakaryocytic thrombocytopenia (CAMT) is characterized by low platelet count (thrombocytopenia), absent or low numbers of megakaryocytes (megakaryocytopenia) and bone marrow failure. CAMT typically presents with a bleeding episode in early infancy. Individuals are at risk for aplastic anemia and leukemia.
A milder presentation of CAMT, known as CAMT II, is characterized by increasing platelet counts that approach near-normal in the first year of life and an onset of bone marrow failure after the age of 3.
Pathogenic MPL variants have also been shown to segregate with autosomal dominant hereditary thrombocythemia. but they are unlikely to be a common cause of thrombocythemia.
The majority of cases of congenital amegakaryocytic thrombocytopenia can be attributed to pathogenic variants identified in MPL.
CAMT is inherited in an autosomal recessive manner.
CAMT is thought to be rare and its exact prevalence is unknown.
MPL testing may be considered in patients with an onset of severe pancytopenia, decreased bone marrow activity, and very low platelet counts at birth or in childhood.
Invitae is a College of American Pathologists (CAP)-accredited and Clinical Laboratory Improvement Amendments (CLIA)-certified clinical diagnostic laboratory performing full-gene sequencing and deletion/duplication analysis using next-generation sequencing technology (NGS).
Our sequence analysis covers clinically important regions of each gene, including coding exons, +/- 10 base pairs of adjacent intronic sequence in the transcript listed below. In addition, analysis covers the select non-coding variants specifically defined in the table below. Any variants that fall outside these regions are not analyzed. Any specific limitations in the analysis of these genes are also listed in the table below.
Based on validation study results, this assay achieves >99% analytical sensitivity and specificity for single nucleotide variants, insertions and deletions <15bp in length, and exon-level deletions and duplications. Invitae's methods also detect insertions and deletions larger than 15bp but smaller than a full exon but sensitivity for these may be marginally reduced. Invitae’s deletion/duplication analysis determines copy number at a single exon resolution at virtually all targeted exons. However, in rare situations, single-exon copy number events may not be analyzed due to inherent sequence properties or isolated reduction in data quality. Certain types of variants, such as structural rearrangements (e.g. inversions, gene conversion events, translocations, etc.) or variants embedded in sequence with complex architecture (e.g. short tandem repeats or segmental duplications), may not be detected. Additionally, it may not be possible to fully resolve certain details about variants, such as mosaicism, phasing, or mapping ambiguity. Unless explicitly guaranteed, sequence changes in the promoter, non-coding exons, and other non-coding regions are not covered by this assay. Please consult the test definition on our website for details regarding regions or types of variants that are covered or excluded for this test. This report reflects the analysis of an extracted genomic DNA sample. In very rare cases, (circulating hematolymphoid neoplasm, bone marrow transplant, recent blood transfusion) the analyzed DNA may not represent the patient's constitutional genome.
|Gene||Transcript reference||Sequencing analysis||Deletion/Duplication analysis|