Twin studies in insulin dependent diabetes and other autoimmune diseases

Primary biliary cirrhosis in monozygotic and dizygotic twins: Genetics, epigenetics, and environment

“…We note that this type of recruitment may be responsible for a higher prevalence of females, and that could lead to an overestimation of CR through an overascertainment of concordant pairs. 41,42 Such biases could be reduced by twin studies based on national or local registries. However, the lack of a reliable register of patients with PBC (as the one recently used for celiac disease 43 ) and of a sensitive 100% reliable noninvasive marker of the disease (5%-15% of patients with PBC lack detectable AMA when tested by indirect immunofluorescence technique 1 ) militate against this approach.…”

Cytokine secretion patterns in twins discordant for Type I diabetes

“…Pairs of identical twins (n = 17, 10 males, 7 females) discordant for Type I diabetes were studied. Monozygosity was established in all the twin pairs as described previously [1]. The mean disease duration of the diabetic twins was 11.1 years (range 1±35 years).…”

“…Table 1 summarises clinical data of the identical twin pairs discordant for Type I diabetes. Of the non-diabetic twins, seven (41 %) were ICA positive and thus at high disease risk [1,5], ten ICA negative non-diabetic twins were at low-disease risk now estimated to be less than 5 % risk for each [1,5]. Therefore the discordant twin pairs could be divided into two subsets, by the low or high diabetes risk of the healthy cotwin.…”

Genetics of Type 1A Diabetes

“…Differences between monozygotic twins must be due to environmental factors, to genetic factors not coded in the germ line (e.g., somatic mutations), or to genes that undergo random rearrangement (e.g., immunoglobulin, T-cell receptor genes). Limitations of twin studies are small sample sizes, assignment of zygosity, and a patient-referral bias leading to over-ascertainment of concordant twin pairs (Hawkes, 1997;Phillips, 1993;Rowe and Leslie, 1995).…”