Non-ketotic hyperglycinemia in two sibs with mild psycho-neurological symptoms

Non-ketotic hyperglycinemia (NKH) has been diagnosed in two sibs. At the age 2:5 years and 1:3 years respectively only moderate psycho-motor retardation and muscular hypotonia were seen in the elderly child while no psycho-neurological symptoms were seen in the younger sib. Neither of the children had convulsions. This observation is in contrast to earlier published cases of this disorder. A summary of earlier published cases of non-ketotic hyperglycinemia is presented.