Thalassemia intermedia is caused by one of the more severe thalassemic genes combined with a milder thalassemic gene. Children with thalassemia intermedia start to develop symptoms later in life than those with thalassemia major, usually becoming pale and developing symptoms around 2 years of age. They are moderately anemic but a large number of the patients survive without regular blood transfusions.

The severity of thalassemia intermedia isn’t determined by hemoglobin levels alone; it also depends on how the individual is feeling, their growth rate and development. Unfortunately, there isn’t a clear distinction between thalassemia intermedia and thalassemia major.