Twin studies adoption

I The occurrence of MDD shows a familial pattern because first-degree relatives of MDD patients are about three times more likely to develop MDD compared with first-degree relatives of normal control individuals. Adoption studies and twin studies reveal that the familial aggregation of MDD is due to genetic influences.5... 

Twin, family and adoption studies have provided compelling evidence that there is genetic as well as environmental risk for developing alcoholism. Genetic and environmental factors contribute approximately equal proportions to risk in both men and women [1],... 

NATURE VERSUS NURTURE TWIN AND ADOPTION STUDIES... 

I Twin and adoption studies are performed to determine the relative effects of genetiG and environment I on diseases. 

No specific genetic abnormality has yet been identified, but it is clear that BPAD runs in families. Twin and adoption studies have confirmed that this family-based risk is primarily genetic in origin. 

Twin, family, and adoption studies have suggested that heritable factors are important in the development of... 

The evidence available from family, twin, and adoption studies supports the existence of genetic factors in the development of primary mood disorders. 

Genetic studies (primarily derived from population, family, twin, and adoptive studies) suggest that certain depressive disorders may have a genetic loading, especially bipolar and imipolar depression. 

Family, twin, and adoption studies have shown the effect of genetic factors in the affective disorders. Some evidence is seen of at least two distinct subgroups, one X-linked and the other transmitted on chromosome 11 (12-18). Reevaluation of the data by the original authors after additional clinical information became available has led to their modification of the conclusions (19). Clinical correlates of the genetic linkage have been reviewed recently (20, 21) and the codistribution of blood groups was also studied (22). 

Collectively, when Murray s findings are teamed with recent advances from biometrically informative twin and adoption studies, the causal significance of SES, for most environments found in industrialized societies, becomes attenuated further. It also motivates the necessity of more general scientific tools. 

Despite the burgeoning of obesity world-wide, it is still only a minority who become clinically obese (see above). Thus there is individual variation with a secular trend . Genetic factors are believed to play a major role in such variation, according to twin, family and adoption studies (Damcott et al. 2003). It has been calculated that up to 80% of the variance in body mass can be attributed to genetic factors. 

Taylor L, Farone SV, Tsuang MT. Family, twin, and adoption studies of bipolar disease. Curr Psychiatry Rep 2002 4 130-133. 

Related to twin studies are so-called adoption studies, which examine the IQ scores of children who were adopted early in life and compare their scores with the IQ scores of both their natural and their adoptive mothers. The adopted child and its... 

The parent l-phosphabicyclo[3,3,l]nonane (99) was synthesized by Issleib s group by the AIBN-catalyzed cyclization of the phosphinodiene as shown in Equation (9). The CH deformation band (1480 cm ) in the IR spectrum indicated that the phosphine and its oxide and sulfide adopt a twin chair conformation <76ZAAC(425)209>. An XRD study of the corresponding sulfide confirmed this conclusion and showed that the chairs were flattened to some extent, apparently hy repulsions between the endo methylenes r cQ — 3.2 A <88AX(C)1435>. 

Genetics clearly play a role in obesity. It has been noted that an adopted child s body weight is usually more similar to the body weight of his or her biological parents than that of his or her adopted parents. Identical twins usually have similar occurrences of obesity. Studies have also shown that fraternal twins do not show this same likelihood of obesity when one twin is overweight, the other is very often not. These examples help demonstrate that genetics play a significant role in obesity. 

Schizophrenia is a disorder of complex genetics. Adoption, twin and family studies carried out over the last 40 years have provided compelling evidence for the heri-tability of schizophrenia [4]. Meta-analysis of the twin... 

---