Tuesday, 20 November 2007

Common situation in genetic counseling

Today, a medical student asked me about her relative was pregnant and she found that her baby had thalassemia from the prenatal screening. Her doctor gave her a chance to terminate the pregnancy. This student shown me the genotype: Hb Malay (Mutation at codon 19)/ Hb E. This is called compound heterozygotes, in contrary to double hetrozygotes that have mutation on different genes. To answer this question, we should know about the severity of phenotypes, effect to mother.Fortunately, thalassemia is one of the most common and the most throughly study genetic diseases, so we have some information to cope with that. But genotype-phenotype correlation is not an easy issue, there are many factors beyond the mutation itself to correctly predict that. Like these situations, Hb Maly/Hb E infants are not severe (thalassemia intermedia), but the characteristics are widely range from asymptomatic, need some blood transfusion or more frequent need of blood transfusion until required iron chelating therapy or splenectomy in mid-life. There is no specific curative treatment for this group, while beta thallassemia major is so severe and will be died in first two or three years of life, so high mortality-procedure dependent like bone marrow transplantation is accepted.
So the best recommendation for this situation is give all the informations needed to make a good decision for those counselee i.e. severity of baby, effect for pregnancy, treatment plan for baby, side effect of termination, choices, etc. And let the families making their own decision because they have to know what is the best way for their future life. Don't use our standard, believes, social issues to force or coercion them.

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