The studv of rare diseases and rare abnormalities is of more valuie in throwing light upon pathological or physiological processes than in furnishing guidance for futuire enc-xunter with the same condition. This principle applies to the study of diseases in the individual, but it applies even more in the case of homogeneous twins, for here the solutions of embryological problems may become appa...

Two Steiner triple systems, each containing precisely one Pasch configuration which, when traded, switches one system to the other, are called twin Steiner triple systems. If the two systems are isomorphic the systems are called identical twins. Hitherto, identical twins were only known for orders 21, 27 and 33. In this paper we construct infinite families of identical twin Steiner triple systems.

Happiness and Genes Many scientists have argued that they can determine to what extent human happiness levels are controlled by genes by comparing the average happiness levels of identical twins raised apart. If we discover that identical twins raised apart tend to be more hedonically similar than fraternal twins raised apart, this is interpreted as evidence for the thesis that genes have a str...

A case of Norrie's disease in an identical twins is reported. No positive family history was obtained. The couple had no other children. The older of the twins died at the age of 9 months of uncertain cause. To the best of my knowledge this is the first case of Norrie's disease reported in Malaysia. And its occurrence in an identical twins is very rare.

Spontaneous regression of retinoblastoma is described in identical twin boys. In the one bilaterally affected child 2 tumours regressed spontaneously, while a third lesion, which developed at a later stage, required treatment in the form of a cobalt plaque. The second child showed spontaneous regression of the single tumour in his only affected eye. The pathogenesis of spontaneous regression is...

T HE OCCURRENCE of multiple cases of chronic myelocytic leukemia in a family is rare and, to our knowledge, has not been reported in identical twins. An analysis of such data may provide evidence for the existence of genetic factors in human leukemia. This is a report of the development of chronic myelocytic leukemia in identical twins and in one of their brothers. (Figure 1 ). In addition, epi...

We report the finding of multiple cerebral aneurysms in a pair of identical twins. One twin had subarachnoid hemorrhage and intracerebral hematoma; her sister had subarachnoid hemorrhage and intraventricular bleeding. Angiography in both cases showed multiple cerebral aneurysms. It is appropriate to recommend a cerebral angiographic examination of an asymptomatic twin after the other twin has s...

Identical male twins are described, one of whom presented with clinical symptoms of Addison's disease whereas the other was shown to have a deficient adrenal cortical response to stimulation tests. Both had positive adrenal cortex antibodies.

A case of concordant oligodendroglioma in monozygotic twins is reported. The twins were also concordant for uterine leiomyoma and one twin partner had fibroadenoma and lipoma of the breast and myelofibrosis. As very few cases of concordant glioma in monozygotic twins have been published and no such cases in dizygotic twins, a genetic influence in the aetiology of glioma can only be suggested.