1. SECTIONS:
2. preface & acknowledgements
3. genetics at a glance
4. contacts, support & testing
5. testing & pregnancy
6. newborn screening
7. cancer in the family
8. cardiovascular conditions
9. chromosomal conditions
10. clotting & bleeding conditions
11. cystic fibrosis
12. diabetes
13. fragile X syndrome and other causes of developmental delay
14. haemoglobinopathies
15. hereditary haemochromatosis
16. neurofibromatosis
17. neurological conditions
18. psychiatric conditions
19. genetics in practice
20. emerging genetic technologies
21. glossary

GP's role

 

• Have up-to-date information about genetic technologies ready to give to patients who
  raise concerns.
• Refer patients to relevant and reliable sources for further information.

 

Personalised medicine: pharmacogenomics

 

1. Small differences in genes between different population groups, or some families within a population
   group, can mean that individuals react differently to drugs.
2. Knowledge of these genetic differences can be used to tailor drug therapy to ensure that an individual
   receives the most appropriate pharmacotherapy: maximizing the likelihood of therapeutic benefit while
   minimising adverse drug events.

 

Applications

 

1. Genes can determine how many drug receptors are produced on or within cells. For example:
2. Women with metastatic breast cancer who over-express the protein product of the gene called HER2 have aggressive disease and a poor prognosis. When HER2 is over-expressed, extra protein receptors are produced on the cell surface. Twenty to 30% of all women with metastatic breast cancer over-express the HER2 protein
3. The drug Herceptin® is a monoclonal antibody against the HER2 gene product. It is thought that Herceptin® works by binding to the receptor sites on the cell surface, thereby limiting the amount of cell division that occurs and preventing the growth of the cancer.

1. Some patients may metabolise drugs faster or slower than others, impacting on the drug efficacy and contributing to side effects. Genetics can influence how someone would react to a medicine prior to giving it. Genetic testing to guide drug prescription is still in its infancy but is a rapidly developing area.
2. For example, the enzyme in the liver which is produced by the gene CYP2D6, controls the metabolism of codeine to morphine, which is the active analgesic metabolite. Variations of the CYP2D6 gene can have an impact on enzyme production and activity
3. People who have low levels of the functioning enzyme metabolise codeine slowly. Codeine therefore remains in their bodies longer than if it was metabolised quickly
4. Slow metabolisers of codeine are more likely to have respiratory side effects
5. The amount of CYP2D6 produced will determine how effective codeine is. Patients who produce low levels of CYP2D6 in the liver will require smaller doses of the drugs that are metabolised by this enzyme, while fast metabolisers will need larger drug doses to get the same effects
6. The enzyme encoded by the CYP2D6 gene also plays a primary role in the metabolism of drugs used to treat severe depression, schizophrenia, bi-polar disorder, cardiovascular disease treated with beta blockers, ADHD, and others.

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