Prevalence of various mutations in beta thalassaemia and its association with haematological parameters

To determine the prevalence of various mutations in beta (beta) thalassaemia and its association with haematological parameters.

A descriptive cross sectional study was carried out in the Department of Haematology, Armed Forced Institute of Pathology (AFIP) from February 2009 to January 2010. A total of 515 carriers having beta thalassaemia mutations characterized by Multiplex amplification refractory mutation system (ARMS) were included in the study. Frequencies of different beta thalassaemia mutations were calculated. Mutations were analyzed for their haematological parameters which include total red blood cell count (TRBC), haemoglobin (Hb), mean cell volume (MCV), mean cell haemoglobin (MCH) and red cell distribution width (RDW).

Frame shift (Fr) 8-9 was the most common mutation found in 183 (35.5%) of patients followed by intervening sequence 1-5 (IVSI-5) in 126 (24.5%) and Fr 41-42 in 76 (14.8%) while IVSII-1 was the least common mutation found in 1 patient. Fr 8-9 was also the commonest mutation in Punjabis and Pathans. Predominant mutation in other ethnic carriers was IVSI-5. Patients with Fr 8-9 mutation had the lowest mean MCV and MCH of 63.7fl and 19.1pg, of all the mutations. Patients with CAP+1 mutation had mean TRBC, Hb, MCV, MCH and RDW of 5.5 x 1012/L, 13.5g/dl, 78.0fl, 24.7pg and 41.9fl respectively.

Fr 8-9 is the most common beta thalassaemia mutation with lowest red cell indices while CAP+1 mutation can present with normal red cell values therefore, a potential carrier should be screened for CAP+1 mutation by DNA analysis.