Vitamin K is a fat-soluble vitamin necessary mainly for the formation of blood clots. Without this vitamin, bleeding would not stop. 

Vitamin K is given as an injection to newborns to prevent vitamin K deficiency bleeding, since the level of blood clotting factors of newborn babies are roughly 30–60% that of adult values. The reason for this discrepancy is due to poor transfer of the vitamin across the placenta, and thus low fetal plasma vitamin K.

Occurrence of vitamin K deficiency bleeding in the first week of the infant's life is estimated at 0.25–1.7%, with a prevalence of 2–10 cases per 100,000 births. Since the vitamin is found in human milk and supplemented in infant formula, the concentration of vitamin K naturally rises within th ...

A landmark study, based on genetic analysis of nearly 65,000 people, has revealed that a person's risk of schizophrenia is increased if they inherit specific variants in a gene related to "synaptic pruning" - the elimination of connections between neurons. The findings represent the first time that the origin of this devastating psychiatric disease has been causally linked to specific gene variants and a biological process. They also help explain decades-old observations: synaptic pruning is particularly active during adolescence, which is the typical period of onset for schizophrenia symptoms, and brains of schizophrenic patients tend to show fewer connections between neurons. The gene, called component 4 (C4), plays a well-known role in t ...