Concordancy rate

MS probably has a genetic component there is a 5% risk for family members of MS patients. Monozygotic twins, who share the same genetic material, are at highest risk, with a 25% to 30% concordance rate.4 However, a straightforward inheritance pattern cannot fully explain the etiology of MS, because only a small proportion of patients have a known family member with MS.4... 

Concordance rate (proportion of correct test results in screening)... 

The concordance rate of mood disorders is 60-80% for monozygotic twins and 14-20% for dizygotic twins. Linkage studies suggest that certain loci on genes and the X chromosome may contribute to genetic susceptibility of bipolar disorder,... 

Because these are quantitative traits, correlation coefficients, rather than concordance rates, are given. 

Keeping these biases in mind, data from twin studies can be used to estimate the heritability of a trait (i.e., the proportion of variation in a trait that can be attributed to genetic fectors). One simple measure of heritability is dz > where concordance rate for... 

MZ twins and Cjj is the concord ce rate for DZ twins. For example, studies of alcoholism show that the concordance rate for MZ twins tends to be 0.6 or higher, whereas it is 0.3 or lower for DZ twins. If these figures are used in the equation, the heritability of alcoholism is estimated to be 0.43. 

Concordance rates are compared in monozygotic (identical) and dizygotic (fraternal) twins to assess the contribution of genes to a trait These rates can be used to estimate heritability, the proportion of variation in a trait caused by genes. 

Twin studies comparing mono- and dizygotic twins have shown concordance rates of between 25 and 87%, depending on the study. Since none of the studies show a concordance rate of 100%, it is clear that non-genetic factors must influence the expression of OCD. 

Mania, manic-depression and depression, which comprise the affective disorders, are relatively common it has been estimated that there is an incidence of at least 2% in most societies throughout the world. There is good evidence to suggest that genetic factors play a considerable role in predisposing a patient to an affective disorder. In a seminal Danish twin register study, in which the incidence of affective disorders was determined in all twins of the same sex born in Denmark between 1870 and 1920, a total of 110 pairs of twins were identified in which one or both had manic-depression. The concordance rates, that is the rate of coexistence of the disorder in twin pairs, for all types of affective disorder were found to be... 

Evidence-based pharmacotherapy provides a succinct appreciation of the benefits of a drug, but rarely takes into account the patient s quality of life. Eor instance, intensive statin therapy is recommended because it reduces the incidence of cardiovascular death (odds ratio 0.86), myocardial infarction (odds ratio 0.84), and stroke (odds ratio 0.82) however, the increased risks for any adverse event (odds ratio 1.44), for abnormalities on liver function testing (odds ratio 4.48), for elevations in CK (odds ratio 9.97) and for adverse events requiring discontinuation of therapy (odds ratio 1.28) are less often taken into account by the prescriber. This example emphasises that individualisation is of the utmost importance to keep an acceptable benefit/risk ratio (Clin Ther 2007 29 253-60). The benefits of evidence-based pharmacotherapy may be obtained whenever concordance/compliance of the patient is adequate. However, concordance rate is slightly higher than 30% for chronic conditions, such as hypertension (Curr Hypertens Rep 2007 9 184-9), indicating that the patient has to be educated about the use of drugs, and therapy has to be individualised. 

Tourette s Syndrome is a familial disorder (Pauls et ah, 1991 Walkup et ah, 1996). Twin and family studies provide evidence that genetic factors are involved in the vertical transmission within families of a vulnerability to TS and related disorders. The concordance rate for TS among monozygotic twin pairs is 50% while the concordance of dizygotic twin pairs is about 10% (Price et ah, 1985). If co-twins with chronic motor tic... 

There are also cross-fostering studies of children of schizophrenic parents, adopted away by nonschizophrenic foster parents, who were compared with adopted children of normal parents raised by schizophrenic foster parents ( 53, 54). Invariably, those children whose biological parents had schizophrenia developed this disorder more frequently than the offspring of nonschizophrenic parents, even when the latter were reared by schizophrenic foster families. In addition, the concordance rate for the illness in schizophrenic monozygotic twins reared apart was comparable with monozygotic twins reared together. These findings leave little doubt of a hereditary factor in schizophrenia. 

Thymidylate synthase protein expression in the primary tumor is not a useful predictor for either thymidylate synthase protein expression or response to 5-fluorouracil therapy in metastatic disease (52,53). Similarly, concordance rates for expression of HER family members ranges from 79% to 56% between primary breast cancer and matched distant... 

Panic disorder affects up to 2% of the population, but less than one-third receive treatment. Panic disorder typically begins in late adolescence or early adulthood but can present in childhood. Onset is rare after age 45. Panic disorder is more prevalent in women, who have perhaps twice the rate in men. Genetic studies demonstrate a 15 to 20% rate of panic disorder in relatives of patients with panic disorder, including a 40% concordance rate for panic disorder in monozygotic twins. 

---