<prompt> Thalassemia occurs due to which mutations -a Missenseb Splicingc Transitiond Frame-shifte Truncationcdabbd  <response>: Thalassemia syndromeAdult 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-ThalassemiaMost 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 mutationsMutations leading to aberrant splicing are the most common cause of β-thalassemia.ii Chain terminator mutationsThis cause premature termination of mRNA translation.iii Promoter region mutationsThis results in transcription defect.B. α-ThalassemiaThe most common cause of reduced a-chain synthesis is deletion of α-globin genes.Rarely nonsense mutation may also cause α-thalassemia. 