Question

Read the scenario then answer the question:

When Ahmad and Amina decided to get married, they were worried that their coming children might suffer from Sickle cell disease, since Amina’s mother had the disease. But the doctor made things clear ….

DOC: “Unfortunately Mr. Ahmad after tracking your family’s genetics you might be carrying the recessive allele for the disease so there is a 25% chance your children might be anemic. “

PARENTS: “ So does that mean that 25% might not even carry the disease allele?

And 50% will carry the allele but won’t have the disease? Did we mention to you that we are cousins? “

Doctor: “ Well now it makes much more sense! Children of first-cousin marriages have an increased risk of autosomal recessive genetic disorders, just like sickle cell disease, which comes from a recessive allele. Two cousins might both carry the recessive allele and transmit it both to their child which will become ill unfortunately, just like sickle cell disease.

PARENTS: “ Unfortunately, my son Seif was born with sickle cell anemia and is getting medication to carry on his life normally. My daughter Shamsa doesn’t suffer from the disease, but she might carry the recessive gene and might have anemic children in the future. “

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INFORMATION:

•You should know that S is the dominant allele for normal blood cells, and s is the recessive allele for sickle cell anemia

•Phenotypes are normal for normal trait and anemic for recessive trait

•In the pedigree we see the cross of the heterozygous parents

question:

Write a neat and full text about your analysis of the family’s inheritance, explain how the disease inheritance is affected by cousins marrying each other, and give solutions to reduce the probability of getting the disease. (350 words)

Enforce your work by doing further research, make sure to insert pictures or any document that you believe can show your work and express your ideas. Do your research on mendelian genetics, inherited diseases, autosomal and gonosomal, patterns of inheritance etc…

Answer 1

Answer: Sickle cell anaemia disease is autosomal recessive disease, that is individuals having ss genotype will have the disease. The carriers of the disease have one allele normal (S) and other allele sickle cell anaemia (s), that is, heterozygous genotype Ss. In this case, both the parents are the carriers of the sickle cell anaemia. Marriage in cousins has greater chance of having the disease as the genetic variations tend to be low. The probability of getting the disease can be reduced by distant marriage relation or one of the parents should not have any family history of sickle cell anaemia. If the genetic variations are higher between the parents there is chance that the unfavourable or diseased causing allele will disappear over generations.

Since both the parents are heterozygous, there is 25% chance of having sickle cell anaemia disease (the ss genotype), 25% of being neither a carrier or a diseased individual (the SS genotype), and 50% of being a carrier (the SS genotype). Since sickle cell anaemia disease is autosomal, there is equal chance of disease occurrences in both male and females. In gonosomal diseases there is higher chance disease occurrence of a particular sex.