The present study aimed to demonstrate the extent to which the activity of a number of enzymes and genetic variation of β-globin genes were affected in the blood of 65 children patient with β - thalassemia major of both sexes, their ages ranged between ( 2 – 15 ), who registered in the Thalassemia Center at Ibn Al-Atheer Teaching Hospital for Children in the city of Mosul / Iraq and who are continuing treatment, after they were diagnosed by specialist doctors, as well as 30 healthy children of both sexes with same ages of the patients and it was considered as a control group.
The results showed a significant increase (P≤0.05) in the activity of Alanine transaminase (ALT), Aspartate transaminase (AST), Alkaline phosphatase (ALP), Glucose 6- phosphate dehydrogenase (G6PD) and Adenosine deaminase (ADA) in the serum of treated children patients with β - Thalassaemia major by 73% , 53%, 8%, 9% and 54% respectively, compared with the healthy children group (control group). Also the results showed a significant increase in the activity of G6PD and ADA in the hemolysis of RBC of the same children patients by 7% and 43% compared with control group.
When determining the genetic variation of the β-globin gene the result which depends on PCR technique did not show any genetic variation in the size of PCR band ,while the result of the sequencing showed variation in the nucleotides and included converted the nucleotide (A) to (C) in position (250) , change nucleotide (T) to (C) in position (426), replacement (C) nucleotide to (A) in position (623), change (G) nucleotide to (A) in position (630) and replacement (T) to (A) in the position (724), also the result detection three Transversion mutation and two transition mutation in β-globin gene in babies with β-thalassemia