Even with treatment, the condition is associated with premature birth and a risk of cerebral palsy in a surviving fetus. Around 5–15% of identical twin fetuses will go on to develop TTTS. The condition was first described by German obstetrician Friedrich Schatz in 1875. Cause
As a result of sharing a single placenta, the blood supplies of monochorionic twin fetuses can become connected, so that they share blood circulation: although each fetus uses its own portion of the placenta, the connecting blood vessels within the placenta allow blood to pass from one twin to the other. It is thought that most monochorionic placentae have these "shared connections" that cross the placenta, with the net flow volumes being equal between them. This state is sometimes referred to as "flow balance". When the placenta has deep vein–artery connection, this can cause blood flow to become unbalanced.Depending on the number, type and direction of the interconnecting blood vessels (anastomoses), blood can be transferred disproportionately from one twin (the "donor") to the other (the "recipient"), due to a state of "flow imbalance" imparted by new blood vessel growth across the placental "equator", the line that divides each babys proportion of the shared placenta. This state of transfusion causes the donor twin to have decreased blood volume, retarding the donors development and growth, and also decreased urinary output, leading to a lower than normal level of amniotic fluid (becoming oligohydramnios).
Mitotane, sold under the brand name Lysodren, is a steroidogenesis inhibitor and cytostatic antineoplastic medication which is used in the treatment of adrenocortical carcinoma and Cushings syndrome. It is a derivative of the early insecticide DDT and an isomer of p,p-DDD (4,4-dichlorodiphenyldichloroethane) and is also known as 2,4-(dichlorodiphenyl)-2,2-dichloroethane (o,p-DDD). Medical uses
Mitotane has been produced by Bristol Myers Squibb but it is marketed as an orphan drug for adrenocortical carcinoma due to the small number of patients in need of it. Its main use is in those patients who have persistent disease despite surgical resection, those who are not surgical candidates, or those who have metastatic disease. In a 2007 retrospective study of 177 patients from 1985 to 2005 showed a significant increase in the recurrence-free interval after radical surgery followed by mitotane when compared to surgery alone. The drug is also sometimes used in the treatment of Cushings syndrome. Side effects
The use of mitotane is unfortunately limited by side effects, which, as reported by Schteinberg et al., include anorexia and nausea (88%), diarrhea (38%), vomiting  (23%), decreased memory and ability to concentrate (50%), rash (23%), gynecomastia (50%), arthralgia (19%), and leukopenia (7%). Pharmacology
Pharmacodynamics
Mitotane is an inhibitor of the adrenal cortex. It acts as an inhibitor of cholesterol side-chain cleavage enzyme (P450scc, CYP11A1), and also of 11β-hydroxylase (CYP11B1), 18-hydroxylase (aldosterone synthase, CYP11B2), and 3β-hydroxysteroid dehydrogenase (3β-HSD) to a lesser extent.