Question

Sickle cell anemia mutation removes a restricton site from the beta-globin gene such that a specific probe hybridizes to one 1.3-kb fragment instead of two fragments of 1.1kb and 0.2 kb. What restriction pattern will be seen in the sickle-cell carriers?

Answer 1

Sickle-cell carriers will have a unique restriction pattern that includes one 1.3-kb fragment from the mutated allele and two normal fragments of 1.1 kb and 0.2 kb, leading to a combination of three distinct bands on gel electrophoresis.

Step-by-step explanation:

The restriction pattern seen in sickle-cell carriers using Cvn-1 endonuclease will include a combination of the normal and sickle cell anemia patterns. These individuals will have both a 1.3-kb fragment from the mutated allele and two additional fragments of 1.1 kb and 0.2 kb from the normal allele. This results in a diagnostic pattern unique to heterozygotes, which would consist of three fragments in total: 1.3 kb, 1.1 kb, and 0.2 kb.

On a molecular level, sickle cell anemia is caused by a single nucleotide substitution that eliminates a restriction site for Cvn-1 in the beta-globin gene, and this forms the basis of DNA diagnosis for the disease. As such, heterozygous individuals (carriers) produce both normal and abnormal hemoglobin due to the presence of one normal beta-globin gene (A) and one mutated gene (a), resulting in varying degrees of anemia symptoms. In the context of genetic testing, identifying these restriction patterns through gel electrophoresis is instrumental in early diagnosis and management of sickle cell trait, particularly for family planning and understanding the potential risks of passing the mutation to offspring.