Genetic counselling
Genetic counselling, or counseling, is how clients are advised about genetic disorders. Genetic disorders, by definition, can be passed on in heredity. Example: many descendents of Queen Victoria carried one or both alleles for haemophilia. It was a hereditary disease in European royal families.
Clients with a disorder may be interested in the probability of transmitting a genetic disorder to their children. They may ask what the options are to prevent, avoid or improve it.
Genetic counsellors
changeFacilities and rules vary in different countries. In the United States the National Society of Genetic Counselors defines genetic counselling as: [1]
- Interpretation of family and medical histories to assess the chance of disease occurrence or recurrence.
- Education about inheritance, testing, management, prevention, resources and research.
- Counselling to promote informed choices and adaptation to the risk or condition.
A genetic counsellor is an expert with a Master of Science degree in genetic counseling. In the United States they are certified by the American Board of Genetic Counseling.[2] Most enter the field from biology, genetics, nursing, psychology, public health and social work. Genetic counsellors need to be expert educators, skilled in translating ideas into terms that are easy to understand.
Reasons and results
changeFamilies may choose to attend counselling or undergo prenatal testing for a number of reasons.[3]
- Family history of inherited disease.
- Molecular test for a single gene disorder
- Increased maternal age (>35 years)
- Abnormal serum screening results or ultrasound findings
Training
changeTraining of genetic counselling is not done in all countries, and the service of genetic counselling is not available in all countries.
The basis
changeThe cost of complete genome analysis has come down so far that individual people can have their own genome analysed.
The problem is interpret what the analysis shows. At present there are many genes whose functions are not yet known, and many alleles whose effect is not known.[4]
Practical consequences
changeAlready it is possible to identify the sex of a foetus in the womb, and to identify some of the most common disorders. This may, depending on legal and religious constraints, influence abortion of the foetus in some cases. In some cases, the effects of a defect can be anticipated and prevented or cured. These issues do not affect most people today, but as genomic analysis advances, genetic counselling will become of much greater significance.
Root causes
changeA number of themes occur. Almost universal is: groups which marry a restricted set of partners tend to have more genetic defects. The two most obvious cases are:
- The royal families of Europe
- Ashkenazi Jews
In the case of royal families there were a number of marriages of cousins and other close relationships. They suffered a disproportionate number of haemophiliacs, and some distorted features such as the Habsburg jaw (prognathism). It has been suggested that the Ancient Egyptian pharaohs suffered short lives because of their frequent incestuous marriages. In this connection it is interesting that Tutankhamun's mother was the full sister of his father.[5] However, the immediate cause of his death seems to be malaria.
Ashkenazi jewery has a very sophisticated understanding of the genetic problems they face, and maintain an excellent advice service.[6][7]
In both cases the key causal element is the restricted set of permissible partners available for marriage.
Related pages
changeReferences
change- ↑ "The process of helping people understand and adapt to the medical, psychological and familial implications of genetic contributions to disease". [1] Archived 2011-01-03 at the Wayback Machine
- ↑ NSGC [2]
- ↑ Macdonald F. 2008. Practice of prenatal diagnosis in the UK. Clin Risk 14(6):218-221.
- ↑ Machácková, Eva (2003). "Disease-causing mutations versus neutral polymorphism: use of bioinformatics and DNA diagnosis". Cas Lek Cesk. 142 (3). Czech Republic: Ceskoslovenska Lekarska Spolecnost: 150–153. PMID 12756842.
- ↑ Hawass, Zahi et al. (17 February 2010). "Ancestry and Pathology in King Tutankhamun's Family" (PDF). The Journal of the American Medical Association. 303 (7): 638–647. doi:10.1001/jama.2010.121. PMID 20159872. Retrieved 27 August 2019.
- ↑ E.L. Abel Jewish genetic disorders: a layman's guide, McFarland, 2008: ISBN 0786440872
- ↑ "Chicago Center for Jewish Genetic Disorders - Jewish Genetic Diseases". 2003-02-16. Archived from the original on 16 February 2003. Retrieved 2022-08-20.