The Prevelence of HBB c.93-21 G-A in β Thalassemia Patients

• The β-thalassaemias result from over 300 gene mutations (Kurtoğlu A,et al 2016)
• These mutations are regionally specific and the spectrum of mutations has been determined for most at-risk populations. The strategy for identifying β-thalassaemia mutations is usually based on knowledge of the common mutations in the ethnic group of the individual being screened (Old JM, 2007).

The β globin gene mutation [HBB:c.93-21G˃A] or IVS I-110 (G>A) is the most common β globin gene mutation in the Mediterranean region (Old JM, 2007). . There is no consensus about the % of the mutation among β thalassemic patients in Egypt [has been reported (25.8%) by El-Gawhary et al. 2007, (33.75%) by Soliman et al. 2010, (48%) by El-Shanshory et al. 2014, (22%) by Elmezayen et al. 2015 and (34%) by Elhalfawy et al. 2017].

According to the HbVar site, it represents 33% of the β globin gene mutations in the Egyptians. 28.5% according to Henderson S ,et al 2009 .

• The mechanism of this mutation depends on formation of a new splicing site resulting in 80% abnormal spliced mRNA and 20% normal mRNA .
• The molecular characterization of the globin gene mutation is necessary for definite diagnosis, genetic counseling, and in prenatal diagnosis.
• The amplification-refractory mutation system (ARMS) is a simple method for detecting any mutation involving single base changes or small deletions.
• The DNA is analyzed after amplification by PCR for Detection of point mutation IVS I-110 (G>A) by Using primer pairs that only amplify individual alleles.