Hemoglobin F Only Syndrome at Birth: A Case of Maternal HbA2' Complicating the Diagnosis of β-Thalassemia.

An asymptomatic infant of Ghanaian descent had hemoglobin F only detected on newborn screening. β-globin gene sequencing identified the intervening sequence (IVS)-II-849 (A → G) mutation with no normal β-globin gene. β-globin/δ-globin gene sequencing showed that both parents were heterozygous for the IVS-II-849 (A → G) mutation. The mother was heterozygous for the HbA2' δ-globin mutation (δ16 (A13) Gly → Arg), thus β-thalassemia trait was unrecognized due to coinheritance of HbA2'. The infant developed anemia, splenomegaly, and began transfusion therapy by the age 6 of months. This is the first report of β-thalassemia major with homozygous IVS-II-849 (A → G) mutations. This case highlights the importance of δ-globin gene mutations in prenatal testing.