HL-A Identical Siblings

communication). Appleyard (1968) showed that babies born after an anoxic delivery developed a significant lowering of the Thrombotest at 24 hours compared with those who were not anoxic during delivery. Possibly the lowered Thrombotest is associated with liver damage due to hypoxia; however, more probably the infants had some degree of disseminated intravascular coagulation resulting from the metabolic acidosis and hypotension associated with intrapartum asphyxia. The intravascular coagulation reduces clotting factors-including prothrombin (factor II), which is consumed-and this will be reflected by a lowered Thrombotest. Some intravascular coagulation undoubtedly occurs in anoxic babies during delivery, as fibrin split products are almost invariably found in the first day of life (M. A. Chadd and S. M. Muxworthy, personal communication). It is suggested that this may be the mechanism in some of the present series. We have several times encountered babies with low Thrombotest who have responded to a dose of fresh frozen plasma by a rise in Thrombotest, but the level has quickly dropped. Some of these babies have shown no sign of haemorrhage at necropsy, so that the rapid drop in factor II level can be explained only by a consumption coagulopathy. The fibrin formed during coagulation, if deposited in small end arteries throughout the brain, could cause multiple areas of cerebral ischaemia, which may explain some of our findings.