A couple seeking premarital genetic counseling:
Male: heterozygous for ∆3.7 single gene deletion mutation (alpha thalassemia trait)
Female: heterozygous for IVS II-1 G>A mutation (beta thalassemia trait)
What would be the phenotype of a kid carrying both traits?
Thank you in advance.
Double heterozygote or alpha+ and beta thalassemia will have less globin chain imbalance than trait of either of them; and so, the clinical and hematological picture will be better than both the parents. Read an interesting case at: Blood Cells, Molecules, and Diseases 32 (2004) 319 – 324
1 in 4 normal
2 with either trait
1 with both traits which would likely cause more sever anemia.
There shouldn't be a clinical problem for offsprings from this marriage - as stated above by Jason Cabot
First part of Jason's answer is correct, but the offspring carrying both traits would not suffer from severe anaemia and would be perfectly fine! He would have 1 functional beta gene and 3 functional aplha genes a situation that is prefectly compensated.
Double heterozygote or alpha+ and beta thalassemia will have less globin chain imbalance than trait of either of them; and so, the clinical and hematological picture will be better than both the parents. Read an interesting case at: Blood Cells, Molecules, and Diseases 32 (2004) 319 – 324
I fully agree with Indu Thakur, Jacques Elion and Ramesh Patel in either case the children will never have more severe phenotypes the contrary the chances are more favorable
Dr Barreiro effectively summarised the different answers to Dr Habbal's question, giving clinically useful information. In my perception, this is the role of RG in our scientific community.
alpha thal trait is almost silent unless associated with an alpha ° thal..( Hb H)
beta trait is a beta ° ones.. but since partner does not carry beta thal , there is no risk of severe beta genotype. So, there is no problem for that couple . The "worse situation" would be double heterozygote which would be less severe than the beta ° thal alone. However, such genotype will be more complicated when the patient will ask for gene counseling. So when he grows up, I will recommend a full genotyping ( alpha and beta) in order to make him able to make a safe parental project.
They can be married without any clinical problem in the future.
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