Beta-thalassemia
Beta thalassemias are due to mutations in the HBB gene on chromosome 11, also inherited in an autosomal, recessive fashion. The severity of the disease depends on the nature of the mutation and on the presence of mutations in one or both alleles. Mutated alleles are called β+ when partial function is conserved (either the protein has a reduced function, or it functions normally but is produced in reduced quantity) or βo, when no functioning protein is produced. The situation of both alleles determines the clinical picture:

β thalassemia major (Mediterranean anemia or Cooley anemia) is caused by a βo/βo genotype. No functional β chains are produced, and thus no hemoglobin A can be assembled. This is the most severe form of β-thalassemia;
β thalassemia intermedia is caused by a β+/βo or β+/β+ genotype. In this form, some hemoglobin A is produced;
β thalassemia minor is caused by a β/βo or β/β+ genotype. Only one of the two β globin alleles contains a mutation, so β chain production is not terribly compromised and patients may be relatively asymptomatic.Beta thalassemia most often occurs in people of Mediterranean origin. To a lesser extent, Chinese, other Asians, and African Americans can be affected. Delta-thalassemia
As well as alpha and beta chains present in hemoglobin, about 3% of adult hemoglobin is made of alpha and delta chains. Just as with beta thalassemia, mutations that affect the ability of this gene to produce delta chains can occur. Combination hemoglobinopathies
Thalassemia can coexist with other hemoglobinopathies.
Tight hymenal ring is a disorder of the hymen, characterized by a rigid hymen and tight introitus, whether acquired or congenital. It excludes an imperforate hymen. The condition can be relieved by outpatient surgery or manual dilation. References


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