A-Level Biology AQA Notes
3.8.4.2 Differences in DNA between individuals of the same species can be exploited for identification and diagnosis of heritable conditions
Diagnosing Heritable Conditions
- Genetic screening is the study of an individual’s DNA to identify whether an individual possesses alleles associated with a genetic disease
- Genetic screening can be carried out using DNA probes which are short sections of DNA that are complementary to a known DNA sequence (e.g. a mutant allele). The probes are labelled using fluorescence or radioactivity
- The labelled DNA probe, which is complementary to a mutant allele, is mixed with denatured DNA samples from a patient. If the patient has the mutant allele, the probe will bind to the complementary base sequence in one strand (hybridization). The hybridized DNA can be detected using radiation or fluorescence.
- DNA probes can be used to screen patient for different genetic diseases, to see if they are carriers for a recessive mutation or to see if they are at risk of developing a disease like cancer, by having mutated oncogenes or tumour suppressor genes.
- Genetic screening also allows medicine or treatments to be precisely tailored to an individual’s genotype (personalised medicine).
- After receiving the results of genetic screening, individuals may require genetic counselling. This is a service that provides support, information and advice about genetic conditions.