Advances in genetic research have led to the identification of an increased number of genetic tests available for adult onset disorders.
Alzheimer disease is an adult-onset progressive dementia. Most cases of the disease are sporadic; some late onset cases show a familial inheritance pattern and about 2% of cases are early onset. Genetic testing is available for early onset Alzheimer disease.
- For more information see our Genetics of Alzheimer Disease PowerPoint education module with referenced speaker’s notes (13,136 KB PowerPoint ) (see instructions for printing)
Diabetes type II
Also known as adult-onset diabetes. Researchers have identified susceptibility genes, but no genetic testing is available at present.
Factor V Leiden
Factor V Leiden is the most common inherited thrombophila. The prevalence varies by geographic region ranging from 1 to 8% and is most common in Caucasians of European ancestry. Individuals with a mutation in the F5 gene have an increased risk for venous thromboembolism.
Hereditary Hemochromatosis (HH)
HH is caused by a mutation in the HFE gene which leads to inappropriately high absorption of iron. Excessive iron storage causes damage to the liver, skin, pancreas, heart, joints, and testes. The classic triad of symptoms are cirrhosis, type 2 diabetes and hyperpigmentation of the skin; symptoms occur between 40 and 60 years of age.
For more information see our Hereditary Hemochromatosis PowerPoint education module with referenced speaker’s notes (1,422 KB PowerPoint ) (see instructions for printing)
Huntington Disease (HD)
HD is a progressive neurodegenerative disorder of motor, cognitive, and psychiatric function. The incidence of HD is about 1 in 10,000. Genetic testing and counselling for the HD gene is available; due to the nature of the disease and limited treatment, genetic counselling and testing are a multi-step process and may include a psychiatric assessment.
Long QT syndrome
Long QT syndrome is characterized by QT prolongation and T-wave abnormalities on the ECG, associated with arrhythmias. Features include syncope, cardiac arrest and sudden death; symptoms may present at any time from newborn to adulthood. Genetic testing is available.
Pharmacogenetics is a new and growing area of medicine. The identification of genes involved in drug metabolism has led to the development of genetic tests to help determine those who may benefit from using certain drugs and those more likely to have harmful side effects.
No single gene has been identified to cause schizophrenia. Currently several potential susceptibility genes have been identified and each gene is thought to make a small contribution to the risk for schizophrenia. 22q11 deletion syndrome (as known as DiGeorge or velocardiofacial syndrome) is a syndrome with variable presentation.
Affected individuals can have some or all of the following:
- birth defects (heart, palate)
- learning or speech problems
- endocrine abnormalities
- subtle differences in facial appearance
- 40-60% develop psychiatric problems ranging from anxiety disorders to schizophrenia.
See Primary Care Resources for more information.