<prompt> Defect in Snurps causes?Sickle cell anemiaThalassemiaMarfan syndromeEDS  <response>: Defective splicing defect in snurps is the most common mutation causing thalassemia. Molecular defect in pathogensis of thalassemia:? A b-Thalassemia Most common type of genetic abnormality in b-thalassemia is point mutation i.e., nonsense. Some may also occur due to deletion or inseion i.e., frame shift mutations. Defect may occur at different steps of b-chain synthesis: i Splicing mutations Mutations leading to aberrant splicing are the most common cause of P-thalassemia. ii Chain terminator mutations This cause premature termination of mRNA translation. iii Promoter region mutations This results in transcription defect. B a-Thalassemia The most common cause of reduced a-chain synthesis is deletion of a-globin genes. Rarely nonsense mutation may also cause a-thalassemia. 