Description　
Alpha-thalassemia is characterized by impaired production of the alpha globin chains of hemoglobin, leading to a relative excess of gamma globin chains (fetus and newborn), or excess beta globin chains (children and adults) mainly due to deletion or mutation of the alpha globin genes. There are four alpha thalassemia syndromes, reflecting the loss of function of one, two, three, or all four of these alpha chain genes varying in severity from non-symptomatic to incompatibility with extrauterine life (Benz Jr & Angelucci, 2020; Martin & Thompson, 2013). 

Beta-thalassemia is similarly characterized by impaired production of hemoglobin components but affects the beta chains instead of the alpha chains. This creates excess alpha globin chains, leading to hemolytic anemia, impaired iron handling, and other clinical symptoms (Benz Jr, 2021).

Background 
Hemoglobin, which is the major oxygen carrying protein molecule of red blood cells, consists of 2 α-globin chains and 2 β-globin chains. Alpha-thalassemia refers to a group of syndromes that arise from deficient production of α-globin chains. Deficient α-globin production leads to an excess of β-globin chains, which results in anemia by a number of mechanisms¹: 

• Ineffective erythropoiesis in the bone marrow. 

• Production of nonfunctional hemoglobin molecules. 

• Shortened survival of RBCs [red blood cells] due to intravascular hemolysis and increased uptake of the abnormal RBCs by the liver and spleen.

The physiologic basis of α-thalassemia is a genetic defect in the genes coding for α-globin production. Each individual carries 4 genes that code for α-globin (2 copies each of HBA1 and HBA2, located on chromosome 16), with the wild genotype (normal) being aa/aa. Genetic mutations may occur in any or all of these 4 α-globin genes. The number of genetic mutations determines the phenotype and severity of the α-thalassemia syndromes. The different syndromes are classified as follows:

• Silent carrier (α-thalassemia minima). This arises from 1 of 4 abnormal alpha genes (aa/a-), and is a silent carrier state. A small amount of abnormal hemoglobin can be detected in the peripheral blood, and there may be mild hypochromia and microcytosis present, but there is no anemia or other clinical manifestations.
• Thalassemia trait (α-thalassemia minor). This is also called α-thalassemia trait and arises from the loss of 2 α-globin genes, resulting on 1 of 2 genotypes (aa/--, or a-/a-). There is a mild anemia present, and red blood cells are hypochromic and microcytic. Clinical symptoms are usually absent and in most cases, the Hg electrophoresis is normal.
• Hemoglobin H disease (α-thalassemia intermedia). This syndrome results from 3 abnormal α-globin genes (a-/--), resulting in a moderate to severe anemia. In HgH disease, there is an imbalance in α- and β-globin gene chain synthesis, resulting in the precipitation of excess β chains into the characteristic hemoglobin H, or β-tetramer. This condition has marked phenotypic variability, but most individuals have mild disease and live a normal life without medical intervention.² 

A minority of individuals may develop clinical symptoms of chronic hemolytic anemia. These include neonatal jaundice, hepatosplenomegaly, hyperbilirubinemia, leg ulcers, and premature development of biliary tract disease. Splenomegaly can lead to the need for splenectomy, and transfusion support may be required by the third to fourth decade of life. It has been estimated that approximately 25% of patients with HgH disease will require transfusion support during their lifetime.³ In addition, increased iron deposition can lead to premature damage to the liver and heart. Inappropriate iron therapy and oxidant drugs should be avoided in patients with HgH disease.

There is an association between genotype and phenotype among patients with HgH disease. Individuals with a nondeletion mutation typically have an earlier presentation, more severe anemia, jaundice, and bone changes, and more frequently require transfusions.⁴

• Hemoglobin Bart syndrome (α-thalassemia major). This syndrome results from mutations in all 4 α-globin genes (--/--), resulting in absent production of α-globin chains. This condition causes hydrops fetalis, which often leads to intrauterine death, or death shortly after birth. There are also increased complications of pregnancy for a woman carrying a fetus with hydrops fetalis. These include hypertension, preeclampsia, antepartum hemorrhage, renal failure, premature labor, and abruption placenta.³ 

Alpha-thalassemia is a common genetic disorder, affecting approximately 5% of the world’s population.³  The frequency of mutations is highly dependent on ethnicity, with the highest rates seen in Asians, and much lower rates in Northern Europeans. The carrier rate is estimated to be 1 in 20 in Southeast Asians, 1 in 30 for Africans, and between 1 in 30 and 1 in 50 for individuals of Mediterranean ancestry. In contrast, for individuals of northern European ancestry, the carrier rate is less than 1 in 1,000.

Genetic Testing
A number of different types of genetic abnormalities are associated with α-thalassemia. More than 100 different genetic mutations have been described. Deletion of 1 or more of the α-globin chains is the most common genetic defect. This is the type of genetic defect found in approximately 90% of cases.⁵ Large genetic rearrangements can also occur from defects in crossover and/or recombination of genetic material during reproduction. Point mutations in 1 or more of the α genes can occur that impair transcription and/or translation of the α-globin chains.

Testing is commercially available through several genetic labs. Targeted mutation analysis for known α-globin gene mutations can be performed by polymerase chain reaction (PCR).^4,5 PCR can also be used to identify large deletions or duplications. Newer testing methods have been developed to facilitate identification of α-thalassemia mutations, such as multiplex amplification methods and real-time PCR analysis.^6-8 In patients with suspected α-thalassemia and a negative PCR test for genetic deletions, direct sequence analysis of the α-globin locus is generally performed to detect point mutations.⁵

Regulatory Status
Genetic testing for alpha thalassemia is available as a laboratory-developed service, subject only to the general laboratory operational regulation under the Clinical Laboratory Improvement Amendments (CLIA) of 1988. Laboratories performing clinical tests must be certified for high-complexity testing under CLIA. The U.S. Food and Drug Administration (FDA) has not regulated these tests to date.

Policy

1. Genetic counseling for alpha- or beta-thalassemia genetic testing is considered MEDICALLY NECESSARY and is recommended.

2. Preconception (carrier) testing for alpha- or beta-thalassemia in prospective parents is considered MEDICALLY NECESSARY when either parent has evidence of possible alpha-thalassemia (including alpha thalassemia minor, hemoglobin H disease [alpha thalassemia intermedia], or alpha thalassemia major) or beta-thalassemia (including beta thalassemia minor, beta thalassemia intermedia, or beta thalassemia major) based on biochemical testing.  

3. Genetic testing to confirm a diagnosis of alpha- or beta- thalassemia is considered MEDICALLY NECESSARY when one of the parents is a known carrier or when other testing to diagnose cause of microcytic anemia has been inconclusive.  

The following does not meet coverage criteria due to a lack of available published scientific literature confirming that the test(s) is/are required and beneficial for the diagnosis and treatment of a patient’s illness.

4. Genetic testing for alpha- or beta-thalassemia in other clinical situations (recognizing that prenatal and newborn testing is not addressed in this policy) is considered NOT MEDICALLY NECESSARY.

Policy Guidelines
This policy does not address prenatal (in utero or preimplantation) genetic testing for α-thalassemia

Biochemical testing to determine whether α-thalassemia is present should be the first step in evaluating the presence of the condition. Biochemical testing consists of complete blood count (CBC), microscopic examination of the peripheral smear, and Hg electrophoresis. In silent carriers and in α-thalassemia trait, the Hg electrophoresis will most likely be normal. However, there should be evidence of possible α-thalassemia minor on the CBC and peripheral smear. 

The probability of a pregnancy with hemoglobin Bart syndrome (α-thalassemia major) is dependent on the specific genotype found in each parent. Table PG1 summarizes the risk according to each category of α-thalassemia.

Table PG1. Risk of α-Thalassemia

Hg: hemoglobin.

Genetic Counseling
Genetic counseling is primarily aimed at patients who are at risk for inherited disorders, and experts recommend formal genetic counseling in most cases when genetic testing for an inherited condition is considered. The interpretation of the results of genetic tests and the understanding of risk factors can be very difficult and complex. Therefore, genetic counseling will assist individuals in understanding the possible benefits and harms of genetic testing, including the possible impact of the information on the individual’s family. Genetic counseling may alter the utilization of genetic testing substantially and may reduce inappropriate testing. Genetic counseling should be performed by an individual with experience and expertise in genetic medicine and genetic testing methods.

Coding
There is a Tier 1 molecular pathology CPT code for testing for common deletions or variants:

81257 - HBA1/HBA2 (alpha globin 1 and alpha globin 2) (eg, alpha thalassemia, Hb Bart hydrops fetalis syndrome, HbH disease), gene analysis, for common deletions or variant (eg, Southeast Asian, Thai, Filipino, Mediterranean, alpha3.7, alpha4.2, alpha20.5, and Constant Spring)

Benefit Application
BlueCard/National Account Issues
The U.S. Food and Drug Administration (FDA) has not regulated these tests because to date they have been offered as laboratory-developed services, subject only to the general laboratory operational regulation under the Clinical Laboratory Improvement Amendments (CLIA) of 1988. Laboratories performing clinical tests must be certified for high complexity testing under CLIA.

Rationale 

Thalassemias result from deficiencies in hemoglobin biosynthesis due to mutations in or near the two globin gene clusters which encode the globin polypeptide subunits of hemoglobin (Benz Jr & Angelucci, 2020). Normal hemoglobin is a heterotetramer of two alpha globin chains and two beta globin chains (hemoglobin A) or two gamma globin chains (hemoglobin F). Well over 100 mutations have been documented to affect the biosynthesis or post-translational stability of the globin subunits needed for successful production of the large amounts of Hb needed for normal red cell homeostasis. Globin chain synthesis is very tightly controlled, such that the ratio of production of alpha to non-alpha chains is almost exactly 1:1 (Benz Jr, 2020).
Alpha thalassemia refers to thalassemias that result from impaired or absent production of alpha globin, leading to a relative excess of gamma globin (fetus and newborn), or excess beta globin (children and adults). Excess beta globin chains can form soluble homotetramers, but they are nonfunctional and unstable. This may lead to increased hemolysis and a variety of clinical manifestations, such as anemia, thrombosis, and skeletal changes. A diagnosis of alpha thalassemia is often confirmed by genetic testing, as assessment of the hemoglobin gene is inexpensive and convenient (Benz Jr, 2020). 
The clinical severity is directly attributable to the net deficit of alpha globin synthesis but is complicated by the number of alpha globin genes affected, which of the two alpha globin loci is affected, and the degree to which the mutation blocks gene expression. In addition, combinations of defects in both alpha and beta globulins can balance each other out. Thus, understanding the broad spectrum of clinical severity in alpha thalassemia requires a detailed knowledge of the underlying genetic defect and the impact of these defects on the overall levels and balance of globin chain synthesis (Benz Jr, 2021).

The majority of cases of alpha thalassemia are attributable to deletion of alpha globin alleles, especially in Asia and Africa (Steinberg, 1999). However, more detailed analysis of globin gene sequences suggests that some fairly common forms of alpha thalassemia that appear to arise from a deletion of one copy of an alpha globin gene are actually due to unequal crossover and recombination events that fuse the two alpha globin genes together into one (Benz Jr, 2020). Additionally, non-deletion alleles are also common, especially in the Mediterranean area, which contain mutations producing highly unstable alpha globin variants unable to produce intact hemoglobin (Benz Jr & Angelucci, 2020). Current research continues to identify novel mutations and improve thalassemia screening (He et al., 2018).

Beta-thalassemia is similar to alpha-thalassemia, with the beta chains of hemoglobin affected instead of the alpha chains. However, excess alpha globin chains do not form soluble homotetramers, causing them to aggregate when they accumulate in erythroid precursors. This causes clinical symptoms to be more severe, although the symptoms themselves are similar to alpha-thalassemia (anemia, iron overload, and so on) (Benz Jr, 2021; Benz Jr & Angelucci, 2020). There are two beta globin genes compared to four for the alpha chain. As with alpha-thalassemia, the severity of clinical presentation depends on the genotype of the beta globin genes (i.e. the ratio of beta to alpha globin chains). Mutations may result in a reduced expression (β+) or absent expression (β0). β0 phenotypes are generally transfusion-dependent as they produce very little (if any) adult hemoglobin (Benz Jr, 2021).
Due to the frequency of thalassemias worldwide, carrier screening may be useful, particularly in areas such as Southeast Asia, Africa, and the Indian subcontinent. Both primary thalassemias are autosomal recessive genetic disorders so parents who are heterozygous carriers would have a 25% chance to have an affected child despite being asymptomatic themselves. Identification of an affected fetus could alter decisions during the pregnancy (Yates, 2021).

Below is a table summarizing the clinical genotypes and phenotypes of both thalassemia syndromes (Benz Jr, 2018; Benz Jr & Angelucci, 2020; Steinberg, 2019) (figure from Benz Jr).

Analytical Validity
He et al. (2017) examined a next-generation sequencing (NGS) panel’s utility for thalassemia screening in Southwestern China. 951 individuals were tested, and the NGS screen found 471 carriers (49.5%) of thalassemia. In comparison, traditional methods (defined as “red cell indexes and hemoglobin electrophoresis, then DNA sequencing”) identified only 209 carriers (22%) of thalassemia, missing 217 alpha-thalassemia carriers and 47 beta-thalassemia carriers (He et al., 2017). In a separate study by Zhang et al. (2019), because of studying 3,973 subjects that underwent hematological examinations and additional NGS and Gap-PCR due to being suspected thalassemia carriers, the researchers found that “approximately 2.88% thalassemia carriers would be missed by traditional genetic analysis. In addition, four novel thalassemia mutations and one novel abnormal hemoglobin mutation were identified.” This research further corroborated the increased effectiveness of using NGS in screening thalassemia in an area of high disease prevalence (Zhang et al., 2019).

Shook et al. (2020) evaluated the accuracy of a specific pattern in hemoglobin separation tests. The authors desired to find if an “FSA” pattern corresponded to a final diagnosis of the sickle cell trait (HbAS), or a final diagnosis of sickle beta-thalassemia (HbSβ+). Traditionally, the FSA pattern has indicated a diagnosis of HbSβ+; however, the authors hypothesized that the FSA pattern truly indicates a diagnosis of HbAS instead. 31 newborns with an initial screening result of the FSA pattern (a suspected diagnosis of HbSβ+) were included. 30 of these newborns underwent protein-base confirmatory testing and 17 underwent confirmatory genetic testing. Of the newborns undergoing protein confirmatory testing, 23 had an “FSA” pattern, establishing a diagnosis of HbAS. Of the 8 remaining newborns with an FSA pattern, 7 underwent genetic testing which identified HbAS as well. Genetic testing also confirmed positive HbAS results in 10 newborns that tested initially positive by protein testing. The authors concluded that genetic testing had utility in newborn screening for hemoglobinopathies (Shook et al., 2020).

Chen et al. (2021) established an effective NGS protocol for four-factor preimplantation genetic testing (PGT) to diagnose α- and β-thalassemia. Three couples, in whom both partners were α- and β-double thalassemia carriers, underwent PGT and a total of 35 biopsied trophectoderm samples underwent multiple displacement amplification (MDA). Using NGS-based single-nucleotide polymorphism (SNP) haplotyping, these samples were analyzed. “51.5% (17/33) of the embryos were diagnosed as unaffected non-carriers or carriers. Of the 17 unaffected embryos, nine (52.9%) were tested further and identified as euploid via NGS-based aneuploid screening, in which five had HLA types matching affected children.” The authors conclude that NGS-SNP was effective in performing PGT for multipurpose detection (Chen et al., 2021). 

Clinical Validity and Utility
Nosheen et al. (2015) evaluated a preliminary screening program for beta-thalassemia. The screening program focused on families of beta-thalassemia major children. 98 samples were taken, and 57 were found to have a beta-thalassemia trait with elevated hemoglobin alpha 2. The mean hemoglobin alpha 2 level of the carriers was 5.2±0.56% compared to 2.34±0.57% in normal subjects. The authors suggested that screening programs and counseling for carriers could decrease incidence of beta-thalassemia major (Nosheen et al., 2015).

Satirapod et al. (2019) evaluated the clinical outcomes of using preimplantation genetic testing (PGT) in couples at risk of passing on beta thalassemia. Two components of PGT were used, PGT for monogenic disease (used for diagnosis) and PGT for aneuploidy (intended to identify chromosomal aberrations) A total of 15 couples were included and a total of 106 embryos were tested. After preimplantation testing, 12 of 15 women were able to obtain satisfactory genetic testing results (defined as non-disease affected embryos without chromosomal aberration and transfer within first two cycles). Of these, 9 women had successful implantations and 8 women had successful pregnancies with live births (deemed a 53.33% success rate). PGT assessment of genetic status was confirmed by pre- and post-natal genetic testing. Overall, the authors concluded that combined PGT-A and PGT-M was a useful technology to prevent beta-thalassemia in the offspring of recessive carriers. To increase the diagnostic efficiency of PGT-M, multiple displacement amplification (MDA) may be utilized as the first step. This conclusion was drawn by Fu et al. (2019), who found in a retrospective cohort study, that from 2,315 embryos tested, MDA yielded a 96.99% diagnostic efficiency, versus a PCR group, which only yielded 88.15%. MDA also enabled statistically significantly more embryos to be available for transfer as well when compared to the PCR group (74.28% vs 64.28%, respectively, P < 0.001) (Fu et al., 2019).

Chen et al. (2020) also conducted a similar study that evaluated “the efficacy of preimplantation genetic testing (PGT) for α- and β-double thalassemia combined with aneuploidy screening using next-generation sequencing (NGS).” From 12 couples that each carried both α- and β- thalassemia mutations, the researchers were able to facilitate 11 healthy live births from examining 112 embryos. This NGS-based SNP (single nucleotide polymorphism) haplotyping was demonstrated to “reduce misdiagnosis by linkage analyses with multiple SNP loci” and increase the number of diagnosis results, including those from detecting aneuploidy and identified mutation sites, in a single PGT cycle. It was also found that NGS-based SNP haplotyping could be performed “through directly detecting mutation sites with NGS and using affected embryos or gametes as probands.” This procedure benefits in eliminating multiple biopsies as well (Chen et al., 2020).

Canadian College of Medical Geneticists (CCMG) and Society of Obstetricians and Gynaecologists of Canada (SOGC) 
The CCMG and SOGC published a joint guideline titled “Joint SOGC–CCMG Opinion for Reproductive Genetic Carrier Screening: An Update for All Canadian Providers of Maternity and Reproductive Healthcare in the Era of Direct-to-Consumer Testing” in 2016. Their recommendations addressing thalassemias/hemoglobinopathies are listed below:

• "Carrier screening for hemoglobinopathies should be offered to women/families from ethnic backgrounds with a reported increased carrier frequency, when red blood cell indices reveal a mean cellular volume < 80 fl, or electrophoresis reveals an abnormal hemoglobin type. However, the use of ethnicity alone in the carrier risk identification process may create screening inconsistency and missed opportunity for carrier identification, with both obstetrical and fetal implications. High clinical suspicion is required as well. Screening should be done in the pre-conception period or as early into the pregnancy as possible. (II-2A) (GRADE moderate/moderate)”

• “Carrier screening for thalassemia/hemoglobinopathies should be offered by the most responsible health care provider or reproductive genetic provider and include: complete blood count, hemoglobin (Hb) electrophoresis (HE) or Hb high performance liquid chromatography (HHPLC), quantification of Hb alpha 2 and fetal Hb, and serum ferritin/H bodies (blood smear stain using brilliant cresyl blue) if microcytosis (mean cellular volume < 80 fl) and/or hypochromia (mean cellular Hb < 27 pg) in the presence of a normal HE or HHPLC assessment. (II-2A) (GRADE moderate/moderate)”

• “If the female thalassemia screening results are abnormal, a hemoglobinopathy screening protocol should be undertaken for the male partner. (III-A) (GRADE low/moderate)”

• “If both reproductive partners are found to be carriers of thalassemia or a combination of thalassemia and hemoglobin variant, they should be referred for formal genetic counselling (reproductive risks, recommended prenatal testing, and diagnostic management). (II-3A) (GRADE moderate/moderate)” (Wilson et al., 2016)

The Thalassemia Longitudinal Cohort 
The report on the Thalassemia Longitudinal Cohort (Tubman et al., 2015) recommends: “Obtaining genotyping to confirm the diagnosis and HLA typing for transplant evaluation for all patients who require chronic transfusion is strongly recommended. For pediatric patients, annual comprehensive follow up should include assessment of the availability of a related donor as well as a recommendation to bank cord blood and obtain HLA typing on all subsequently born full siblings.”

American College of Obstetrics and Gynecology (ACOG) 
The ACOG Committee Opinion #691 (“Carrier Screening for Genetic Conditions”) states that: “Couples at risk of having a child with a hemoglobinopathy may benefit from genetic counseling to review their risk, the natural history of these disorders, prospects for treatment and cure, availability of prenatal genetic testing, and reproductive options. Prenatal diagnostic testing for the mutation responsible for sickle cell disease is widely available. Testing for α-thalassemia and β-thalassemia is possible if the mutations and deletions have been previously identified in both parents. These DNA-based tests can be performed using chorionic villi obtained by chorionic villus sampling or using cultured amniotic fluid cells obtained by amniocentesis. For some couples, preimplantation genetic diagnosis in combination with in vitro fertilization may be a desirable alternative to avoid termination of an affected pregnancy. Preimplantation genetic diagnosis has been successfully performed for sickle cell disease and most types of β-thalassemia” (ACOG, 2017). This was reaffirmed in 2020.

In 2018, ACOG reaffirmed its practice bulletin regarding hemoglobinopathies in pregnancy (originally published in 2007) (ACOG, 2018). The following recommendations are considered “Level A” and based on “good and consistent scientific evidence”. 

• “Individuals of African, Southeast Asian, and Mediterranean descent are at increased risk for being carriers of hemoglobinopathies and should be offered carrier screening and, if both parents are determined to be carriers, genetic counseling.”

• “A complete blood count and hemoglobin electrophoresis are appropriate laboratory tests for screening for hemoglobinopathies. Solubility tests alone are inadequate for screening because they fail to identify important transmissible hemoglobin gene abnormalities affecting fetal outcome.”

• “Couples at risk for having a child with sickle cell anemia or thalassemia should be offered genetic counseling to review prenatal testing and reproduction options. Prenatal diagnosis of hemoglobinopathies is best accomplished by DNA analysis of cultured amniocytes or chorionic villi.”

ACOG also writes that “if the MCV [mean corpuscular volume] is below normal, iron deficiency anemia has been excluded, and the hemoglobin electrophoresis is not consistent with β-thalassemia trait (ie, there is no elevation of Hb A2 or Hb F), then DNA-based testing should be used to detect α-globin gene deletions characteristic of α-thalassemia”. ACOG remarks that neither hemoglobin electrophoresis nor solubility testing can identify individuals with the α-thalassemia trait, only molecular genetic testing can (ACOG, 2007).

The Association of Public Health Laboratories (APHL) 
Molecular testing can be added to resolve cases when the newborn has been transfused with packed red blood cells. Since the newborn’s phenotype is masked by the donor, DNA testing can be used to identify any abnormal hemoglobins (APHL, 2015).

National Health Service (NHS)
NHS states that first, the mean cell hemoglobin (MCH) must be measured in a screening for thalassemia. The NHS presents this decision tree of when to test for thalassemia:

“1. Is the MCH <25pg?

2. Is the woman’s family origin identified as high risk from the Family Origin Questionnaire: China (including Hong Kong), Southeast Asia (especially Thailand, Taiwan, Cambodia, Laos, Vietnam, Burma, Malaysia, Singapore, Indonesia or Philippines), Cyprus, Greece, Sardinia, Turkey, or unknown?
If the answer to both questions is yes, testing of the baby’s biological father must be offered if he is also from a high-risk area or unknown.

If the baby’s biological father is suspected of having a0 thalassaemia, the samples on both biological parents must be sent for DNA analysis for a0 thalassaemia mutations.

If one biological parent is a suspected carrier of a0 thalassaemia and the other is a carrier of a thalassaemia and is also from one of the high-risk groups for a0 thalassaemia with an MCH < 25pg, both biological parents should be screened for a0 thalassaemia by DNA analysis.”

The NHS states that 99% of a0 thalassemia cases have an MCH of < 25 pg. However, the NHS acknowledges that this algorithm may miss some beta-thalassemia carriers (NHS, 2017).

Public Health England (PHE) 
The PHE highlights the importance of antenatal screening. If the baby’s mother is identified as a carrier, the biological father should also be tested. Both prenatal diagnosis and genetic counselling are recommended by the PHE (PHE, 2021).

British Society for Haematology (BSH) 
The BSH provides the following recommendations:

• “Antenatal screening/testing of pregnant women should be carried out according to the guidelines of the NHS Sickle Cell and Thalassaemia Screening programme.

• Laboratories performing antenatal screening should utilize methods capable of detecting significant variants and be capable of quantitating haemoglobins A 2 and F at the cut‐off points required by the national antenatal screening program” (Ryan et al., 2010).

Genetic counseling is also permitted for prospective parents.

The Thalassemia International Foundation (TIF)
The TIF provided recommendations for the management of transfusion dependent Thalassemia. The following recommendations were made (TIF, 2021): 

• “Molecular genetic testing is available in clinical laboratories and may be useful for predicting the clinical phenotype in some cases as well as enabling presymptomatic diagnosis of at-risk family members and prenatal diagnosis.

• Molecular analysis is not required to confirm the diagnosis of a β carrier, but it is necessary to confirm the α thalassemia carrier status (grade A)

• Since the prevalent pathogenic variants of the β globin gene are limited in each at-risk population, a PCR method designed to detect the common specific mutation simultaneously should be used initially (grade B)

• β globin gene sequence analysis may be considered first if the affected individual is not of an ancestry at high risk or if targeted analysis reveals only one or no pathogenic variant (grade B)

• α thalassemias are mainly due to deletions of different length and they can be detected preferentially by reverse dot blot and Gap-PCR (grade B)

• Methods that may be used to detect rare or unknown deletions include: Southern blotting (now fallen into abeyance), quantitative PCR, long-range PCR and, above all, MLPA (grade B)” (TIF, 2021). 

Table of Terminology

References  

1. ACOG. (2007). ACOG Practice Bulletin No. 78: hemoglobinopathies in pregnancy. Obstet Gynecol, 109(1), 229-237. https://doi.org/10.1097/00006250-200701000-00055 

2. ACOG. (2017). ACOG Commitee Opinion 691: Carrier Screening for Genetic Conditions. Obstet Gynecol, 129, e41-e55. https://doi.org/10.1097/AOG.0000000000001952 

3. ACOG. (2018). ACOG Publications. Obstetrics & Gynecology, 131(1). https://journals.lww.com/greenjournal/Fulltext/2018/01000/ACOG_Publications.31.aspx 

4. APHL. (2015). Hemoglobinopathies: Current Practices for Screening, Confirmation and Follow-up. Association of Public Health Laboratories Retrieved from https://www.cdc.gov/ncbddd/sicklecell/documents/nbs_hemoglobinopathy-testing_122015.pdf

5. Benz Jr, E. J. (2018). Classical thalassemia syndromes (genotypes and laboratory findings). In UpToDate. Waltham. MA.

6. Benz Jr, E. J. (2020, March 27). Molecular pathology of the thalassemic syndromes. https://www.uptodate.com/contents/molecular-genetics-of-the-thalassemia-syndromes

7. Benz Jr, E. J. (2021, January 7). Pathophysiology of thalassemia. https://www.uptodate.com/contents/pathophysiology-of-thalassemia

8. Benz Jr, E. J., & Angelucci, E. (2020, January 17). Clinical manifestations and diagnosis of the thalassemias. https://www.uptodate.com/contents/clinical-manifestations-and-diagnosis-of-the-thalassemias

9. Chen, D., Shen, X., Wu, C., Xu, Y., Ding, C., Zhang, G., Xu, Y., & Zhou, C. (2020). Eleven healthy live births: a result of simultaneous preimplantation genetic testing of α- and β-double thalassemia and aneuploidy screening. Journal of assisted reproduction and genetics, 37(3), 549-557. https://doi.org/10.1007/s10815-020-01732-7 

10. Chen, D., Shen, X., Xu, Y., Ding, C., Ye, Q., Zhong, Y., Xu, Y., & Zhou, C. (2021). Successful four-factor preimplantation genetic testing: α- and β-thalassemia, human leukocyte antigen typing, and aneuploidy screening. Systems Biology in Reproductive Medicine, 67(2), 151-159. https://doi.org/10.1080/19396368.2020.1832158 

11. Fu, Y., Shen, X., Chen, D., Wang, Z., & Zhou, C. (2019). Multiple displacement amplification as the first step can increase the diagnostic efficiency of preimplantation genetic testing for monogenic disease for β-thalassemia. J Obstet Gynaecol Res, 45(8), 1515-1521. https://doi.org/10.1111/jog.14003 

12. He, J., Song, W., Yang, J., Lu, S., Yuan, Y., Guo, J., Zhang, J., Ye, K., Yang, F., Long, F., Peng, Z., Yu, H., Cheng, L., & Zhu, B. (2017). Next-generation sequencing improves thalassemia carrier screening among premarital adults in a high prevalence population: the Dai nationality, China. Genet Med, 19(9), 1022-1031. https://doi.org/10.1038/gim.2016.218 

13. He, S., Li, J., Li, D. M., Yi, S., Lu, X., Luo, Y., Liang, Y., Feng, C., Chen, B., Zheng, C., & Qiu, X. (2018). Molecular characterization of alpha- and beta-thalassemia in the Yulin region of Southern China. Gene, 655, 61-64. https://doi.org/10.1016/j.gene.2018.02.058 

14. Martin, A., & Thompson, A. A. (2013). Thalassemias. Pediatr Clin North Am, 60(6), 1383-1391. https://doi.org/10.1016/j.pcl.2013.08.008 

15. NHS. (2017). NHS Sickle Cell and Thalassaemia Screening Programme. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/656094/Antenatal_Laboratory_Handbook.pdf

16. Nosheen, A., Ahmad, H., Qayum, I., Siddiqui, N., Abbasi, F. M., & Iqbal, M. S. (2015). Premarital genetic screening for beta thalassemia carrier status of indexed families using HbA2 electrophoresis. J Pak Med Assoc, 65(10), 1047-1049. 

17. PHE. (2021, January 7). Sickle cell and thalassaemia screening: commission and provide. https://www.gov.uk/government/collections/sickle-cell-and-thalassaemia-screening-commission-and-provide

18. Ryan, K., Bain, B. J., Worthington, D., James, J., Plews, D., Mason, A., Roper, D., Rees, D. C., de la Salle, B., & Streetly, A. (2010). Significant haemoglobinopathies: guidelines for screening and diagnosis. Br J Haematol, 149(1), 35-49. https://doi.org/10.1111/j.1365-2141.2009.08054.x 

19. Satirapod, C., Sukprasert, M., Panthan, B., Charoenyingwattana, A., Chitayanan, P., Chantratita, W., Choktanasiri, W., Trachoo, O., & Hongeng, S. (2019). Clinical utility of combined preimplantation genetic testing methods in couples at risk of passing on beta thalassemia/hemoglobin E disease: A retrospective review from a single center. PLoS One, 14(11), e0225457. https://doi.org/10.1371/journal.pone.0225457 

20. Shook, L. M., Haygood, D., & Quinn, C. T. (2020). Clinical Utility of Confirmatory Genetic Testing to Differentiate Sickle Cell Trait from Sickle-beta(+)-Thalassemia by Newborn Screening. Int J Neonatal Screen, 6(1). https://doi.org/10.3390/ijns6010007 

21. Steinberg, M. H. (1999). Management of sickle cell disease. N Engl J Med, 340(13), 1021-1030. https://doi.org/10.1056/nejm199904013401307 

22. Steinberg, M. H. (2019, December 5). Structure and function of normal hemoglobins. https://www.uptodate.com/contents/structure-and-function-of-normal-hemoglobins

23. TIF. (2021). 2021 GUIDELINES FOR THE MANAGEMENT OF TRANSFUSION DEPENDENT THALASSAEMIA (TDT). https://www.thalassemia.org/boduw/wp-content/uploads/2021/06/TIF-2021-Guidelines-for-Mgmt-of-TDT.pdf 

24. Tubman, V. N., Fung, E. B., Vogiatzi, M., Thompson, A. A., Rogers, Z. R., Neufeld, E. J., & Kwiatkowski, J. L. (2015). Guidelines for the Standard Monitoring of Patients with Thalassemia: Report of the Thalassemia Longitudinal Cohort. J Pediatr Hematol Oncol, 37(3), e162-169. https://doi.org/10.1097/mph.0000000000000307 

25. Wilson, R. D., De Bie, I., Armour, C. M., Brown, R. N., Campagnolo, C., Carroll, J. C., Okun, N., Nelson, T., & Zwingerman, R. (2016). Joint SOGC–CCMG Opinion for Reproductive Genetic Carrier Screening: An Update for All Canadian Providers of Maternity and Reproductive Healthcare in the Era of Direct-to-Consumer Testing. Journal of Obstetrics and Gynaecology Canada, 38(8), 742-762.e743. https://doi.org/10.1016/j.jogc.2016.06.008 

26. Yates, A. (2021, March 9). Prenatal screening and testing for hemoglobinopathy. https://www.uptodate.com/contents/prenatal-screening-and-testing-for-hemoglobinopathy

27. Zhang, H., Li, C., Li, J., Hou, S., Chen, D., Yan, H., Chen, S., Liu, S., Yin, Z., Yang, X., Tan, J., Huang, X., Zhang, L., Fang, J., Zhang, C., Li, W., Guo, J., & Lei, D. (2019). Next-generation sequencing improves molecular epidemiological characterization of thalassemia in Chenzhou Region, P.R. China. Journal of clinical laboratory analysis, 33(4), e22845-e22845. https://doi.org/10.1002/jcla.22845

Coding Section  

Procedure and diagnosis codes on Medical Policy documents are included only as a general reference tool for each policy. They may not be all-inclusive.

This medical policy was developed through consideration of peer-reviewed medical literature generally recognized by the relevant medical community, U.S. FDA approval status, nationally accepted standards of medical practice and accepted standards of medical practice in this community, Blue Cross and Blue Shield Association technology assessment program (TEC) and other non-affiliated technology evaluation centers, reference to federal regulations, other plan medical policies, and accredited national guidelines.

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