AP PSYCHOLOGY

Detailed explanation-1: -Concordance rates between monozygotic twins are reported to be approximately 30–65% compared with 5–15% in dizygotic twins. Therefore if one twin has schizophrenia, the relative risk for the other twin may increase to 50 in monozygotic twins and to ∼5–15 in dizygotic twins.

Detailed explanation-2: -[2] Analyzing classic studies of the genetics of schizophrenia done as early as in 1930s, Fischer concludes that a concordance rate for psychosis of about 50% in monozygotic twins seems to be a realistic estimate, which is significantly higher than that in dizygotic twins of about 10–19%.

Detailed explanation-3: -Terms in this set (31) concordance rates for schizophrenia among monozygotic (identical) twins (MZ) are signicantly higher than among dizygotic (fraternal) twins (DZ). Major problem in such studies is separating heredity factors from environmental inuences. Some schizophrenics show brain deterioration.

Detailed explanation-4: -Probandwise concordance rates of 25.3% (SE ± 4.4) for monozygotic (MZ), 5.4% (±2.8) for dizygotic (DZ), and 2.9% (±0.6) for their nontwin siblings were found.

Detailed explanation-5: -Samples from the same individual or identical twins theoretically have a concordance of 100%, but due to assaying errors and somatic mutations, they are usually found in the range of 99% to 99.95%.