Evaluate how genetic screening identifies alleles early, helping diagnosis, risk assessment and reproductive decisions while considering the evidence and limitations in Cambridge A Level Biology questions.
The polymerase chain reaction (PCR) is used to produce large quantities of DNA from a very small original sample. The main steps of one PCR method are shown in Fig. 4.1.
Fig. 4.1
The presence of a faulty allele of the gene B R C A 2 can lead to an increased chance of developing breast cancer. There are many different faulty alleles of the gene BRCA2.
People who are considered to be at risk of breast cancer may choose to be tested for the presence of these alleles in their genomes.
A microarray can be used to test blood samples for the presence of these alleles. The microarray contains DNA probes for different faulty alleles of the BRCA2 gene.
Outline the advantages of screening for faulty alleles of the BRCA2 gene.