Identical and Nonidentical Twins: Risk and Factors Involved in Development of Islet Autoimmunity and Type 1 Diabetes

OBJECTIVE

There are variable reports of risk of concordance for progression to islet autoantibodies and type 1 diabetes in identical twins after one twin is diagnosed. We examined development of positive autoantibodies and type 1 diabetes and the effects of genetic factors and common environment on autoantibody positivity in identical twins, nonidentical twins, and full siblings.

RESEARCH DESIGN AND METHODS

Subjects from the TrialNet Pathway to Prevention Study (N = 48,026) were screened from 2004 to 2015 for islet autoantibodies (GAD antibody [GADA], insulinoma-associated antigen 2 [IA-2A], and autoantibodies against insulin [IAA]). Of these subjects, 17,226 (157 identical twins, 283 nonidentical twins, and 16,786 full siblings) were followed for autoantibody positivity or type 1 diabetes for a median of 2.1 years.

RESULTS

At screening, identical twins were more likely to have positive GADA, IA-2A, and IAA than nonidentical twins or full siblings (all P < 0.0001). Younger age, male sex, and genetic factors were significant factors for expression of IA-2A, IAA, one or more positive autoantibodies, and two or more positive autoantibodies (all P ≤ 0.03). Initially autoantibody-positive identical twins had a 69% risk of diabetes by 3 years compared with 1.5% for initially autoantibody-negative identical twins. In nonidentical twins, type 1 diabetes risk by 3 years was 72% for initially multiple autoantibody-positive, 13% for single autoantibody-positive, and 0% for initially autoantibody-negative nonidentical twins. Full siblings had a 3-year type 1 diabetes risk of 47% for multiple autoantibody-positive, 12% for single autoantibody-positive, and 0.5% for initially autoantibody-negative subjects.

CONCLUSIONS

Risk of type 1 diabetes at 3 years is high for initially multiple and single autoantibody-positive identical twins and multiple autoantibody-positive nonidentical twins. Genetic predisposition, age, and male sex are significant risk factors for development of positive autoantibodies in twins.

A Type 1 Diabetes Genetic Risk Score Predicts Progression of Islet Autoimmunity and Development of Type 1 Diabetes in Individuals at Risk

OBJECTIVE

We tested the ability of a type 1 diabetes (T1D) genetic risk score (GRS) to predict progression of islet autoimmunity and T1D in at-risk individuals.

RESEARCH DESIGN AND METHODS

We studied the 1,244 TrialNet Pathway to Prevention study participants (T1D patients' relatives without diabetes and with one or more positive autoantibodies) who were genotyped with Illumina ImmunoChip (median [range] age at initial autoantibody determination 11.1 years [1.2-51.8], 48% male, 80.5% non-Hispanic white, median follow-up 5.4 years). Of 291 participants with a single positive autoantibody at screening, 157 converted to multiple autoantibody positivity and 55 developed diabetes. Of 953 participants with multiple positive autoantibodies at screening, 419 developed diabetes. We calculated the T1D GRS from 30 T1D-associated single nucleotide polymorphisms. We used multivariable Cox regression models, time-dependent receiver operating characteristic curves, and area under the curve (AUC) measures to evaluate prognostic utility of T1D GRS, age, sex, Diabetes Prevention Trial-Type 1 (DPT-1) Risk Score, positive autoantibody number or type, HLA DR3/DR4-DQ8 status, and race/ethnicity. We used recursive partitioning analyses to identify cut points in continuous variables.

RESULTS

Higher T1D GRS significantly increased the rate of progression to T1D adjusting for DPT-1 Risk Score, age, number of positive autoantibodies, sex, and ethnicity (hazard ratio [HR] 1.29 for a 0.05 increase, 95% CI 1.06-1.6; P = 0.011). Progression to T1D was best predicted by a combined model with GRS, number of positive autoantibodies, DPT-1 Risk Score, and age (7-year time-integrated AUC = 0.79, 5-year AUC = 0.73). Higher GRS was significantly associated with increased progression rate from single to multiple positive autoantibodies after adjusting for age, autoantibody type, ethnicity, and sex (HR 2.27 for GRS >0.295, 95% CI 1.47-3.51; P = 0.0002).

CONCLUSIONS

The T1D GRS independently predicts progression to T1D and improves prediction along T1D stages in autoantibody-positive relatives.

Compulsive personality as predictor of response to serotonergic antidepressants

A short paper of this title reported a study by Ansseau et al (1991). The present authors were invited to comment upon the study.

Monoamine oxidase inhibitors: have they a place, have they a future?

The legacy of the hepatotoxic effect and the "cheese reaction" of monoamine oxidase inhibitors still overshadows these useful drugs, despite near-resolution of many of the problems. This short article reviews the indications, adverse effects and progress and future of these agents in psychopharmacology.

Psychotropic drugs

Psychotropic drugs are but one of our tools in treatment and when appreciating articles or books about these compounds, it is always stimulating to see that the author(s) know as much about people and the disorders they are treating as about the drugs which they are using. It is also helpful when the separation between symptomatic and curative treatment is made, and “comfort” and “cure” are distinguished. Papers which help doctors help patients rather than those of somewhat esoteric interest have more appeal, and I think we may ask: Does the author relate this to the work of the clinic and ways to assist the next patient?

Surgical technic for the resection of internal carotid aneurysms using an internal shunt

A technic for reconstruction of the internal carotid artery after resection of carotid aneurysms is presented. Reconstruction is performed over an internal shunt using a vein or Dacron patch. Total interruption of cerebral circulation is usually less than three minutes. The technic is described in detail. Oculoplethysmographic and phonoangiographic follow-up studies demonstrate normal carotid flow.

Cranial measurements in patients with depressive illness

Cranial measurements and somatotype indices were compared in two groups of patients, one with recurrent depressive illness and the other suffering from a first solitary attack of depression. Certain statistically significant differences in stature, somatotype and cranial measurements emerged; the group with recurrent episodes of depression tended to be shorter and more brachycephalic than those with solitary episodes of depression.

Anxiety state or masked depression? A study based on the action of monoamine oxidase inhibitors

In 1959, West and Dally reported the effects of iproniazid in depressive syndromes, drawing attention to the greater therapeutic effectiveness of this drug in ‘atypical’ or ‘hysterical’ depressive states than in endogenous depression. Later, Sargant and Dally (1962) found a group of patients with good previous personalities, showing obvious features of depression, whose anxiety symptoms responded to phenelzine alone, but in view of the response of other patients with anxiety they questioned whether monoamine oxidase inhibitors were really antidepressant, or whether they were essentially drugs acting against anxiety. These findings prompted this study, intended to compare other parts of the clinical pictures of anxiety states responsive to monoamine oxidase inhibitors with those of depressive illnesses.