You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Thalassemia occurs due to which mutations -a)  Missenseb)  Splicingc)  Transitiond)  Frame-shifte) Truncation and explain in detail?
Thalassemia syndrome

Adult hemoglobin is a tetramer, composed of two α globin chains and two β globin chains.
Thalassemia is an inherited autosomal recessive disorder.
In thalassemia, the genetic defect results in reduced β synthesis of one of the globin chains of hemoglobin.
β-Thalassemia is caused by deficient synthesis of β-chain with normal β-chain synthesis.
α-thalassemia is caused by deficient synthesis of α-chain with normal β-chain synthesis.
Molecular defect in pathogensis of thalassemia.

A. β-Thalassemia

Most common type of genetic abnormality in β-thalassemia is point mutation i.e., nonsense.
Some may also occur due to deletion or insertion i.e., frame shift mutations.
Defect may occur at different steps of β-chain synthesis.

(i) Splicing mutations

Mutations leading to aberrant splicing are the most common cause of β-thalassemia.

(ii) Chain terminator mutations

This cause premature termination of mRNA translation.

(iii) Promoter region mutations

This results in transcription defect.

B. α-Thalassemia

The most common cause of reduced a-chain synthesis is deletion of α-globin genes.
Rarely nonsense mutation may also cause α-thalassemia.