Test ID: HAPB
Hemophilia A, Molecular Analysis for Inversion, Diagnosis and Carrier Detection
Secondary ID 
A test code used for billing and in test definitions created prior to November 2011
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
Identifying the disease-causing mutation in males with severe hemophilia A
Determining hemophilia A-carrier status for individuals with a family history of F8 intron 1 or 22 inversions
Prenatal testing for hemophilia A when there is a high risk of inheriting an F8 intron 1 or 22 inversion and the fetus is male
Genetics Test Information Provides information that may help with selection of the correct test or proper submission of the test request
Detects the common inversion mutations within the factor VIII gene approximately 47% of affected males with severe hemophilia A have been shown to have an inversion.
We recommend this test be used first on an affected family member before carrier testing is done for at risk individuals.
Reflex Tests Lists test(s) that may or may not be performed, at an additional charge, depending on the result and interpretation of the initial test(s)
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| FBC | Fibroblast Culture for Genetic Test | Yes | No |
| AFC | Amniotic Fluid Culture/Genetic Test | Yes | No |
| MCC | Maternal Cell Contamination, B | Yes | No |
Testing Algorithm Delineates situation(s) when tests are added to the initial order. This includes reflex and additional tests.
For prenatal specimens only: If amniotic fluid (non-confluent cultured cells) is received, amniotic fluid culture/genetic test will be added and charged separately. If chorionic villus specimen (non-confluent cultured cells) is received, fibroblast culture for genetic test will be added and charged separately. For any prenatal specimen that is received, maternal cell contamination studies will be added.
The following algorithms are available in Special Instructions:
-Hemophilia Carrier Testing Algorithm
-Hemophilia Testing Algorithm
Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test
Method Name A short description of the method used to perform the test
Intronic inversions within the factor VIII gene are identified by Southern blot analysis.
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
DNA Analysis for Hemophilia A
F8
Factor VIII Deficiency
Factor VIII Inversion
Hemophilia A, Carrier Detection and Prenatal Diagnosis
Severe Hemophilia A
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Forms:
1. Molecular Genetics-Congenital Inherited Diseases Patient Information Sheet (Supply T521) in Special Instructions
2. New York Clients-Informed consent is required. Please document on the request form or electronic order that a copy is on file. An Informed Consent for Genetic Testing (Supply T576) is available in Special Instructions.
3. If not ordering electronically, submit a Molecular Genetics Request Form (Supply T245) with the specimen.
Specimen must arrive within 96 hours of collection.
Submit only 1 of the following specimens:
Specimen Type: Whole blood
Container/Tube:
Preferred: Lavender top (EDTA) or yellow top (ACD)
Acceptable: Any anticoagulant
Specimen Volume: 3 mL
Collection Instructions:
1. Invert several times to mix blood.
2. Send specimen in original tube.
Specimen Stability Information: Ambient (preferred)/Refrigerated
Due to the complexity of prenatal testing, consultation with the laboratory is required for all prenatal testing. Prenatal specimens can be sent Monday through Thursday and must be received by 5 p.m. CST on Friday in order to be processed appropriately. All prenatal specimens must be accompanied by a maternal blood specimen. Order MCC/88636 Maternal Cell Contamination, Molecular Analysis on the maternal specimen.
Specimen Type: Amniotic fluid
Container/Tube: Amniotic fluid container
Specimen Volume: 20 mL
Specimen Stability Information: Refrigerated (preferred)/Ambient
Specimen Type: Chorionic villi
Container/Tube: 15-mL tube containing 15 mL of transport media
Specimen Volume: 20 mg
Specimen Stability Information: Refrigerated
Acceptable:
Specimen Type: Confluent cultured cells
Container/Tube: T-25 flask
Specimen Volume: 2 flasks
Collection Instructions: Submit confluent cultured cells from another laboratory.
Specimen Stability Information: Ambient (preferred)/Refrigerated
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | NA |
| Lipemia | NA |
| Icterus | NA |
| Other | NA |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Varies | Varies | |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Hemophilia A is one of the most common inherited bleeding disorders in humans, affecting approximately 1 in 5,000 males. Common clinical symptoms for individuals with hemophilia A include prolonged oozing after tooth extraction, surgery or injuries, and renewed bleeding at wound sites. It is an X-linked condition in which carrier females are at risk to have affected sons but are typically asymptomatic themselves.
The clinical severity of hemophilia A correlates closely with the plasma concentration of factor VIII, an important factor in the coagulation process. Factor VIII activity levels of <1% are associated with severe disease, 1% to 5% activity with moderate disease, and 5% to 40% with mild hemophilia A. In males with severe deficiency, spontaneous bleeding into the joints can occur, resulting in a progressive arthropathy if untreated. Males with mild to moderate disease have variable onset of prolonged oozing and other bleeding issues but typically do not have spontaneous bleeding. Although rare, some carrier females may have mild symptoms. Approximately 10% of carrier females have a factor VIII clotting activity levels lower than 35% and are at risk for bleeding.
Factor VIII is encoded by the factor VIII gene (F8). Approximately 98% of patients with a diagnosis of hemophilia A are found to have a mutation in the F8 gene (ie, intron 1 and 22 inversions, point mutations, insertions, and deletions). Literature suggests that intron 22 inversions account for approximately 45% and intron 1 inversions account for approximately 2% to 3%, of mutations associated with severe hemophilia A. These inversions are typically not identified in patients with mild or moderate hemophilia A. Inversion analysis is the recommended first-tier molecular test for individuals with severe hemophilia A.
It is recommended that the F8 mutation be confirmed in the affected male or obligate carrier female prior to testing at-risk individuals. Obligate carrier females are identified by family history assessment and affected males by factor VIII activity and clinical evaluation. If this assay does not detect an inversion in these individuals, additional analysis (ie, F8 gene sequencing) may be able to identify the familial mutation. Of note, not all females with an affected son are germline carriers of an F8 mutation as de novo mutations in the F8 gene do occur. Approximately 20% of mothers of isolated cases do not have an identifiable germline F8 mutation. Importantly, there is a small risk for recurrence even when the familial F8 mutation is not identified in the mother of the affected patient due to the possibility of mosaicism.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
An interpretive report will be provided which will include a risk analysis (probability of being a carrier).
Interpretation Provides information to assist in interpretation of the test results
An interpretive report will be provided that includes specimen information, pedigree information (when appropriate), assay information, whether test results are consistent with a diagnosis or positive carrier status, and an estimate of residual carrier risk, when appropriate.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
The technology used in this assay detects only intron 1 and 22 inversion mutations. Thus, a negative result does not exclude the presence of other mutations in the F8 gene.
The intron 22 inversion detected in this direct analysis is found in about 45%, and intron 1 inversions account for approximately 2% to 3%, of individuals with severe hemophilia A; the assay may be uninformative for a number of families.
Any error in the diagnosis or in the pedigree provided will lead to an erroneous segregation pattern and an incorrect interpretation of the results.
Medical genetic or hemophilia center consultation is available for all possible hemophilia A cases and is particularly indicated in complex cases or in situations in which the diagnosis is atypical or uncertain.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Castaldo G, D'Argenio V, Nardiello P, et al: Haemophilia A: molecular insights. Clin Chem Lab Med 2007;45(4):450-461
2. Lakich D, Kazazian Jr HH, et al: Inversions disrupting the factor VIII gene are a common cause of severe hemophilia A. Nature Genetics 1993;5(3):236-241
3. Antonarakis SE, Rossiter JP, Young M, et al: Factor VIII gene inversions in severe hemophilia A: results of an international consortium study. Blood 1995;86(6):2206-2212
Method Description Describes how the test is performed and provides a method-specific reference
Southern blot analysis with the DNA probe 482.6 is used to detect an inversion in a portion of the 3' end of the F8 gene. (Antonarakis SE, Rossiter JP, Young M, et al: Factor VIII gene inversions in severe hemophilia A: results of an international consortium study. Blood 1995;86:2206-2212; Naylor J, Brinke A, Hassock S, et al: Characteristic mRNA abnormality found in half the patients with severe hemophilia A is due to large DNA inversions. Hum Molec Gent 1993;2:1773-1778; Lakich D, Kazazian HH, Antonarakis SE, et al: Inversions disrupting the Factor VIII gene are a common cause of severe hemophilia A. Nat Genet 1993;5:236-241)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Friday; 12 p.m.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
81403-F8 (coagulation factor VIII ) (eg, hemophilia A), inversion analysis, intron 1 and intron 22A
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| 16515 | Specimen | 31208-2 |
| 16516 | Specimen ID | N/A |
| 16517 | Source | N/A |
| 16518 | Order Date | N/A |
| 16519 | Reason For Referral | 42349-1 |
| 16520 | Method | In Process |
| 16521 | Result | 21672-1 |
| 16522 | Interpretation | 69047-9 |
| 16523 | Amendment | In Process |
| 16524 | Reviewed By: | N/A |
| 16525 | Release Date | N/A |
External
link
PDF
document
Excel
document
Word
document