CPT® Code 81269

HBA1/HBA2 (alpha globin 1 and alpha globin 2) (eg, alpha thalassemia, Hb Bart hydrops fetalis syndrome, HbH disease), gene analysis; duplication/deletion variants

The CPT® Code 81269 pertains to molecular genetic testing specifically aimed at analyzing the HBA1 and HBA2 genes, which are crucial for the production of alpha globin chains in hemoglobin. These genes are located on chromosome 16 within the alpha globin locus and are associated with various hemoglobin disorders, including alpha thalassemia, Hb Bart hydrops fetalis syndrome, and HbH disease. The testing focuses on identifying duplication and deletion variants of these genes, which can lead to significant clinical implications. Alpha thalassemia is the most prevalent variant globally, characterized by a reduction or absence of alpha globin chain production due to deletions affecting the HBA1 and HBA2 genes. Various specific deletions, such as SEA, THAI, FIL, MED, and alpha20.5, involve the loss of both HBA1 and HBA2 from the same chromosome, while other variants like alpha3.7 and alpha4.2 result in the deletion of a single alpha gene. The Constant Spring (HbCS) variant is notable for a mutation that extends the protein structure by 31 amino acids. The inheritance pattern of these disorders is autosomal recessive, meaning that individuals must inherit mutations from both parents to develop the associated hemoglobin disorders. Carriers, who inherit a mutation from only one parent, may not exhibit symptoms but can pass the mutation to their offspring. The clinical significance of these disorders varies, with severe forms like Hb Bart leading to hydrops fetalis syndrome and perinatal death, while milder forms may present as microcytic anemia. Molecular genetic testing is essential for diagnosing these conditions, particularly in individuals exhibiting symptoms of hemoglobin disorders, women with a history of fetal loss linked to hydrops fetalis syndrome, or those with a family history of these genetic conditions.