Alpha-Globin Gene Deletion or Duplication

• Consider eliminating iron deficiency anemia as a possibility.
• In the absence of iron deficiency, there may be other genetic causes for abnormal RBC indices and HPLC results. Point mutations in the alpha 1 and alpha 2 genes may be present. Alpha-Globin Gene Sequencing (test code 16116X [16117X for NY]) can detect point mutations in these genes. Please call 1.866.GENE.INFO (1.866.436.3463) to discuss the case, the patient’s indices, and additional testing options.

Both parents must be carriers of a thalassemia mutation for a pregnancy to be at risk. For example, if one parent carries an alpha-globin triplication (5 alpha gene copies) and the other parent carries a beta zero mutation, the fetus could be at risk for beta-thalassemia intermedia. The partner should be screened to determine his/her hemoglobinopathy carrier status (Hemoglobinopathy Evaluation; test code 35489X). Molecular genetic testing may also be appropriate for the partner. Please call 1.866.GENE.INFO (1.866.436.3463) to discuss the case with a genetic counselor.

For family planning purposes, it is important to determine which gene deletions are present and to distinguish whether the deletions are in cis or in trans. The Alpha-Globin Common Mutation Analysis test (test code 11175 [11174 for NY]) can detect the seven most common deletions and identify whether the deletions are in cis or in trans. This will help assess whether a fetus could be at risk for alpha-thalassemia major or hemoglobin H disease, if the partner is also an alpha-thalassemia carrier.