What is the role of genetic factors in the development of Parkinson disease (PD)?

Updated: Jan 24, 2019
  • Author: Robert A Hauser, MD, MBA; Chief Editor: Selim R Benbadis, MD  more...
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Answer

If genetic factors are important in a particular disease, concordance in genetically identical monozygotic (MZ) twins will be greater than in dizygotic (DZ) twins, who share only about 50% of genes. Early Parkinson disease twin studies generally found low and similar concordance rates for MZ and DZ pairs.

However, genetic factors in Parkinson disease appear to be very important when the disease begins at or before age 50 years. In a study of 193 twins, overall concordance for MZ and DZ pairs was similar, but in 16 pairs of twins in whom Parkinson disease was diagnosed at or before age 50 years, all 4 MZ pairs, but only 2 of 12 DZ pairs, were concordant. [7]


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