A congenital contiguous gene deletion syndrome, which is a form of alpha-thalassemia characterized by microcytosis, hypochromia, normal hemoglobin level or mild anemia, associated with developmental abnormalities. Caused by large deletions on chromosome band 16p13.3 which remove the alpha-globin genes (HBA1 and HBA2), and many other flanking genes. The gene(s) responsible for intellectual deficiency and other developmental abnormalities has not been clearly identified. All cases are due to de novo deletions or segregation for parental translocations inherited in an unbalanced manner. The prognosis is highly variable, depending on the degree of intellectual deficiency.