GET INFORMED! Sickle Cell Disease: Where do you get it from?

GET INFORMED! 

Sickle Cell Disease: Where do you get it from?

by Maya Bryant

For “Part Two” of the Sickle Cell Disease series, we will discuss how genetics play a part.  Earlier, we learned how blood cells work, the definition of sickle cell disease, and a few statistics on the disease.  If you haven’t had a chance to look at Part 1, take a second to scroll down and read it right now!  This would help you understand this new section much better.  Now, we are going to discuss DNA and how Sickle Cell Disease is acquired through genetics.

DNA

DNA stands for deoxyribonucleic acid.  It is a molecule that makes up the genetic material of all living things that is found in each and every cell.  DNA is a like a cell’s blueprint: it contains instructions for a cell’s structure and function.  Each person’s DNA contains alleles from each parent. Half of each parent’s alleles are randomly selected to be passed on to the child. (½ alleles from father + ½ alleles from mother = child’s DNA makeup) 

Dominant vs. Recessive Traits 

Each allele has various forms.  This explains why everyone looks different. There is a large variety of each genetically express trait.  Some alleles are dominant and others are recessive. In order for the recessive trait to be expressed, two recessive alleles from each parent have to be passed down to the offspring. In other for a dominant trait to be expressed, the offspring could have both dominant alleles for the trait or a dominant allele and a recessive allele.  The dominant allele DOMINATES over the recessive allele.  For example, brown eyes are a dominant trait and blue eyes are recessive.  If a child was passed down a brown eye allele from their father and a blue eye allele from their mother, the child would have brown eyes, but will still be able to pass down either allele to its offspring.  Complicated right? 

Genetics and Sickle Cell Disease

Sickle Cell Disease is a recessive trait, which means both parents have to pass on a recessive allele for Hemoglobin S (as we discussed in the first segment) to the offspring.  If one dominant and one recessive allele are passed, the offspring has the trait for sickle cell.  This means that the child is able to produce normal red blood cells with Hemoglobin A.  They also may produce some sickle cells here and there, but not enough to harm any bodily functions.  Because the trait can still be passed along, two parents with the sickle cell trait have a 25% chance of having a child with the disease.