A couple, with a family history of beta thalassemia major in a distant relative, has come for counseling. The husband has HbA2 of 4.8% and the wife has HbA2 of 2.3%. The risk of having a child with beta thalassemia major is:
- Normal percentage of HbA2 ranges from 1.5 to 3%. - In thalassemia trait (b thalassemia minor), HbA2 level may be elevated (3.5-7.5%). - Thus, wife in this question has normal genotype (b,b) whereas husband has thalassemia - trait (b+,b). - b-Thalassemia is an autosomal recessive disease. So, None of the offsprings will have thalassemia major (b+ b+), risk of having a child with thalassemia major is 0%. 50% of the offspring (b+,b) will be carriers like father.
50%
25%
5%
0%
Beta thalasemmia