Both α and β thalassemias are often inherited in an
autosomal recessive fashion, although this is not always the case. Cases of
dominantly
inherited α and β thalassemias have been reported, the first of which
was in an Irish family with two deletions of 4 and 11 bp in exon 3
interrupted by an insertion of 5 bp in the β-globin gene. For the
autosomal recessive
forms of the disease, both parents must be carriers in order for a
child to be affected. If both parents carry a hemoglobinopathy trait,
there is a 25% risk with each pregnancy for an affected child.
Genetic counseling and
genetic testing is recommended for families that carry a thalassemia trait.
There are an estimated 60-80 million people in the world carrying the beta thalassemia trait alone.
This is a very rough estimate; the actual number of
thalassemia major patients is unknown due to the prevalence of thalassemia in less developed countries.
Countries such as India and Pakistan are seeing a large increase of
thalassemia patients due to lack of genetic counseling and screening.
There is growing concern that thalassemia may become a very serious
problem in the next 50 years, one that will burden the world's blood
bank supplies and the health system in general.
There are an estimated 1,001 people living with
thalassemia major in the United States and an unknown number of carriers.
Because of the prevalence of the disease in countries with little
knowledge of thalassemia, access to proper treatment and diagnosis can
be difficult.
