Haemoglobinopathy is a kind of genetic defect that results in abnormal structure of one of the globin chains of the haemoglobin molecule. Haemoglobinopathies are inherited single-gene disorders; in most cases, they are inherited as autosomal co-dominant traits. Common haemoglobinopathies include sickle-cell disease.
Haemoglobinopathies imply structural abnormalities in the globin proteins themselves. Thalassemias, in contrast, usually result in underproduction of normal globin proteins, often through mutations in regulatory genes. The two conditions may overlap, however, since some conditions which cause abnormalities in globin proteins (haemoglobinopathy) also affect their production (thalassemia). Thus, some haemoglobinopathies are also thalassemias, but most are not.
Either haemoglobinopathy or thalassemia, or both, may cause anaemia. Some well-known haemoglobin variants such as sickle-cell anaemia and congenital dyserythropoietic anaemia are responsible for diseases, and are considered haemoglobinopathies. However, many haemoglobin variants do not cause pathology or anaemia, and thus are often not classed as haemoglobinopathies, because they are not considered pathologies. Haemoglobin variants are a part of the normal embryonic and foetal development, but may also be pathologic mutant forms of hemoglobin in a population, caused by variations in genetics. Other variants cause no detectable pathology, and are thus considered non-pathological variants. Source: Wikipedia