q14 - kola

[ArchivalUser]

Sickle cell anemia (141900) is caused by a point mutation in the hemoglobin gene, resulting in the substitution of a single amino acid in the β-globin peptides of hemoglobin. This mutation is best detected by which of the following?
1. Isolation of DNA from red blood cells followed by polymerase chain reaction (PCR) amplification and restriction enzyme digestion

2. Isolation of DNA from blood leukocytes followed by Southern blot analysis to detect globin gene exon sizes

3. Isolation of DNA from blood leukocytes followed by DNA sequencing of globin gene introns

4. Isolation of DNA from blood leukocytes followed by polymerase chain reaction (PCR) amplification and allele-specific oligonucleotide (ASO) hybridization

5. Western blot analysis of red blood cell extracts

[ArchivalUser]

is it 2??

[ArchivalUser]

try again

[ArchivalUser]

4.

[ArchivalUser]

1???

[ArchivalUser]

The Correct Answer is: Isolation of DNA from blood leukocytes followed by polymerase chain reaction (PCR) amplification and allele-specific oligonucleotide (ASO) hybridization
Explanation:



Sickle cell anemia (141900) is an autosomal recessive hemoglobinopathy with an incidence of 1 in 500 African American births. It is caused by a single-nucleotide substitution in codon 6 of the β-globin gene. This mutation abolishes an enzyme site so that a larger DNA fragment is obtained after Southern blot analysis with the appropriate enzyme. Single-nucleotide substitutions do not change the length of coding regions (exons). The amplification of DNA segments using the polymerase chain reaction (PCR) allows more sensitive detection of restriction enzyme differences, and can be followed by allele-specific oligonucleotide (ASO) hybridization to determine the presence of normal versus sickle alleles. The equivalence of DNA in most tissues (with the exception of red blood cells that extrude their nucleus) makes DNA diagnosis a powerful technique that is independent of gene or protein expression. Western blotting is a technique that uses antibodies to highlight the size and amount of mutant protein in cell extracts. Since single nucleotide changes in the gene may not affect protein size or conformation, western blotting is generally less sensitive and specific than DNA diagnosis.

[ArchivalUser]

Sickle cell anaemia , blood luecocyte??? doesn't it seem wrong??

[ArchivalUser]

monty it is a tricky q because RBCs have no DNA.

[ArchivalUser]

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