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

Parkinson disease

 

Clinical features

1. Individuals with onset before 20 years of age are considered to have juvenile-onset Parkinson disease.
   
2. Those with onset before 50 years of age are classified as having early-onset Parkinson disease.
   
3. Those with onset after age 50 years are considered to have late-onset Parkinson disease.

 

Genetics

1. 70 to 90% of cases are sporadic.
   
2. The majority of cases with a family history do not have a clear inheritance pattern and could be the result of exposure to common environmental factors and/or a genetic predisposition, or simply a chance familial aggregation.
   
3. Some cases of juvenile/early-onset Parkinson disease have been shown to be due to mutations in the parkin gene which follow a pattern of autosomal recessive inheritance.
   
4. A very few cases of the condition have been shown to be due to mutations in the α-synuclein gene and follow a pattern of autosomal dominant inheritance.

 

Prevalence

1. Affects more than 1% of individuals 55 years of age and more than 3% of those over 75 years of age, but may also affect younger people.

 

Investigations

1. Genetic testing for Parkinson disease is not currently available outside research protocols.

 

Management

1. Referral to a neurogenetics service or Genetics Services may be considered for families with unusual features, such as familial aggregation and/or early-onset Parkinson disease.

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