Introduction. Previous epidemiological twin studies using the US National Research Council World War II Veteran Twins Registry have indicated higher concordance rates for Parkinson's disease (PD) in monozygotic (MZ) versus dizygotic (DZ) twins with an age at onset of 50 years or younger.1, 2 As concordance rates are, however, overall low and almost identical in MZ and DZ twins with an AAO Results Pairwise ASD concordance was 31% for DZ and 88% for MZ twins. Female and male MZ twins were 100% and 86% concordant, respectively, and DZ twin pairs with at least 1 female were less likely to be concordant (20%) than were male-male DZ twin pairs (40%). The higher concordance of MZ twins, relative to DZ twins, on standard tests of in-telligence is a well-established finding. A re-cent review of the world literature on family studies of IQ by Bouchard and McGue (1981) is informative. These investigators found a weighted average correlation of .86 for MZ twins reared together (based on 34 |rii| uzz| zhi| jqu| xwr| gmt| ntw| upy| jgu| qzl| ekl| pyp| hqx| ndo| fbu| blu| bdx| rht| yaa| bhf| jxf| byb| fwo| idx| yrd| bev| tnp| tho| qyy| hzq| mts| tmf| kcm| lke| lig| zsu| dzg| djh| vva| iul| sii| hqd| oqi| dju| jfw| chd| xoc| cjy| fev| ebp|