 |
FAQ: What is the
turnaround time for the Ambry Test: Beta Globin?
Results are
reported in
10-21 days. |
|
 |
Hemoglobin Disorders |
 Hemoglobin
Disorders
Disorders involving hemoglobin are among the
most common genetic disorders worldwide, with approximately
5 percent of the world’s population being carriers for
clinically important hemoglobin mutations. Genes involved
are those that control the production of proteins known as
globins, contained in hemoglobin. Hemoglobin production
involves two sets of genes on different chromosomes that
produce two different pairs of protein; adult hemoglobin is
composed of 2 alpha and 2 beta chains. Hemoglobin contained
within the red blood cells binds oxygen reversibly and
controls the cell’s capacity to transport oxygen to the
tissues. Approximately 500 beta globin mutations have been
discovered, many of which cause serious clinical effects.
Mutations in the DNA sequences controlling
beta globin synthesis can:
- produce structurally abnormal
hemoglobins (e.g., sickle-cell anemia)
- decrease the rate of hemoglobin
synthesis (e.g., thalassemia)
- impair the developmental modification
from fetal to adult hemoglobin (e.g., hereditary
persistence of fetal hemoglobin)
Sickle Cell Disease
The term sickle cell disease encompasses a
group of symptomatic disorders associated with mutations in
the HBB gene. Sickle cell disease is inherited in an
autosomal recessive manner and causes red blood cells to
become deformed (sickle-shaped). The red blood cells distort
because they contain an abnormal type of hemoglobin ―
hemoglobin S, instead of the normal hemoglobin ― hemoglobin
A. Sickled blood cells are destroyed by the body faster than
normal blood cells, which can lead to the body receiving an
inadequate supply of oxygen; this condition is called sickle
cell anemia. Also, sickled blood cells can become trapped in
blood vessels, reducing or blocking blood flow. This can
damage organs, muscles, and bones and may lead to
life-threatening conditions.
Most individuals with sickle cell disease are
healthy at birth and become symptomatic later in infancy or
childhood after fetal hemoglobin (Hb F) levels decrease and
hemoglobin S (Hb S) levels increase. The diagnosis of sickle
cell disease is suspected in infants or young children with
painful swelling of the hands and feet, pallor, jaundice,
pneumococcal sepsis or meningitis, severe anemia with
splenic enlargement, or acute chest syndrome.
Approximately 80,000 Americans have sickle
cell disease. HBB alleles associated with sickle cell
disease are common in African, Mediterranean, Middle
Eastern, and Indian ethnicities as well as in persons from
the Caribbean and parts of Central and South America. In the
US, 1 out of 10 African Americans have sickle cell trait and
1 out of 625 newborns are affected with the disease.
Thalassemia
Beta-thalassemia involves a diverse group of
disorders that interfere with the body's production of
hemoglobin. b-thalassemias are
caused by mutations in the beta globin gene that result in
decreased or absent production of beta globin proteins. It
is an inherited blood disorder, passed from parent to child.
To have the disease, you must inherit one gene mutation for
the disease from each parent.
Most people who inherit thalassemia are
Asian, Filipino, Mediterranean, Middle Eastern, or of
African descent. b-Thalassemia
mutations are population specific: each ethnic group has its
own subset of common mutations.
Thalassemia is sometimes called Mediterranean
anemia or Cooley’s anemia, named after the physician who
first described it. b-thalassemia
is one of the most common inherited diseases worldwide.
|
|
The Ambry Test®: Beta Thalassemia Plus
|
The Ambry Test: Beta Thalassemia Plus is
a cost-effective, comprehensive test method for detection of
mutations within the coding region of the beta globin gene (HBB)
and the surrounding intronic sequences. In addition, the 619
bp East Indian deletion del619 is detected.
The test aids in the diagnosis of hemoglobinopathies
and provides a solid basis for proper therapy.
When a patient has had an abnormal hematological
analysis, molecular genetic testing of the HBB gene can be performed
by Ambry Genetics in order to identify the disease-causing mutation(s).
Identification of specific beta globin mutations can confirm a
differential diagnosis and improve care for the patient as well as
for the patient’s family. The test can also be used following inconclusive
hemoglobin electrophoresis screening to clarify the patient’s disease status.
Early and accurate diagnosis of b-thalassemia is currently the best tool
for decreasing morbidity and mortality from this disease.
The following CPT Codes for The Ambry Test reflects
Ambry Genetics’ interpretation of CPT coding requirements
based on AMA guidelines:
Ambry Test: Beta Globin (HBB)
83891, 83894, 83898, 83904, 83909, 83912
CPT codes are provided only as a guide to
assist you in billing. CPT coding is the sole responsibility of
the billing party.
Disclaimer:
This test was developed and its performance characteristics were determined by Ambry Genetics Corporation. The laboratory is regulated under the Clinical Laboratory Improvement Amendments 2003 as qualified to perform nonwaived testing. Although molecular tests are highly accurate, rare diagnostic errors may occur. The Ambry Test analyzes the following types of mutations (nucleotide substitutions, small deletions, small insertions, and small indels) and is not intended to analyze the following types of mutations (gross insertions, gross deletions except for the del619 mutation, gross rearrangements, and other unknown abnormalities). The pattern of mutation types varies with the gene tested and the Ambry Test detects a high but variable percentage of known and unknown mutants of the classes stated. A negative result from the analysis can not rule out the possibility that the tested individual carries a rare unexamined mutation or mutation in the undetectable group. The Ambry Test: Beta Thalassemia Plus is designed and validated to be capable of detecting about 97-99% of the disease-causing mutations (considering the other ~1-3% to be gross abnormalities, variants in non-coding regions including introns and untranslated sequences, gross deletions, or unknown abnormalities). Beta-hemoglobinopathies are complex clinical disorders, which in the majority of cases are due to alterations in the beta globin gene generally detected by the Ambry Test: Beta Thalassemia Plus except as noted above. Mutations in other genes or non-coding regions not tested by the Ambry Test: Beta Thalassemia Plus can also give rise to similar or identical clinical conditions. Possible diagnostic errors include sample mix-up, erroneous paternity identification, technical errors, and genotyping errors. Genotyping errors can result from trace contamination of PCR reactions, from maternal cell contamination in fetal samples, from rare genetic variants, which interfere with analysis, or from other sources. This report does not represent medical advice. Any questions, suggestions, or concerns regarding interpretation of results should be forwarded to a genetic counselor, medical geneticist, or physician skilled in interpretation of the relevant medical literature. References are available upon request.
|
|
