Physical and occupational therapy may be needed long term.Prosthetics may help some people with ABS to live more functional lives. The price and complexity of these prosthetics vary dramatically, but advances in 3-D printing have helped to increase the availability of artificial fingers while reducing their cost of production. Prognosis
The prognosis depends on the location and severity of the constricting bands. Every case is different and multiple bands may be entangled around the fetus. Bands which wrap around fingers and toes can result in syndactyly or amputations of the digits. In other instances, bands can wrap around limbs causing restriction of movement resulting in clubbed feet. In more severe cases, the bands can constrict the limb causing decreased blood supply and amputation. Amniotic bands can also sometimes attach to the face or neck causing deformities such as cleft lip and palate. If the bands become wrapped around the head or umbilical cord it can be life-threatening for the fetus. The number of cases of miscarriage that can be attributed to ABS is unknown, although it has been reported that it may be the cause of 178 in 10,000 miscarriages. Up to 50% of cases have other congenital anomalies including cleft lip, cleft palate, and clubfoot deformity. Hand and finger anomalies occur in up to 80%. Epidemiology
The reported incidence of constriction ring syndrome varies from 1/1200 and 1/15000 live births.
P elongation occurs through the breaking of all hydrogen bonds involved in the β-turn.The hinge region of antithrombin in the Figure 5 complex could not be modelled due to its conformational flexibility, and amino acids P9-P14 are not seen in this structure. This conformational flexibility indicates an equilibrium may exist within the complex between a P14 P15 reactive site loop inserted antithrombin conformation and a P14 P15 reactive site loop expelled conformation. In support of this, analysis of the positioning of P15 Gly in the Figure 5 complex (labelled in model B) shows it to be inserted into beta sheet A (see model C). Effect of glycosylation on activity
α-Antithrombin and β-antithrombin differ in their affinity for heparin. The difference in dissociation constant between the two is threefold for the pentasaccharide shown in Figure 3 and greater than tenfold for full length heparin, with β-antithrombin having a higher affinity. The higher affinity of β-antithrombin is thought to be due to the increased rate at which subsequent conformational changes occur within the protein upon initial heparin binding. For α-antithrombin, the additional glycosylation at Asn-135 is not thought to interfere with initial heparin binding, but rather to inhibit any resulting conformational changes.Even though it is present at only 5–10% the levels of α-antithrombin, due to its increased heparin affinity, it is thought that β-antithrombin is more important than α-antithrombin in controlling thrombogenic events resulting from tissue injury. Indeed, thrombin inhibition after injury to the aorta has been attributed solely to β-antithrombin.