Non-ketotic hyperglycinaemia: Glycine/serine ratio in amniotic fluid–an unreliable method for prenatal diagnosis

We describe a prenatal diagnosis of a fetus at risk for non-ketotic hyperglycinaemia based on the glycine/serine ratio in amniotic fluid at 16 weeks of gestation. Although the glycine level and the glycine/serine ratio in amniotic fluid were within the normal range, the fetus was affected and therefore a false-negative prediction was made. The reliability of this method is questioned.     

Ontogenetic data and the evolutionary origin of the mammalian scapula

One of the most useful diagnostic therian features is the division of the lateral surface of the scapula into two fossae separated by a scapular spine. A new model to describe this evolutionary innovation based on ontogenetic data is provided, consistent with information provided by recent fossil discoveries. The development of the scapula in three didelphid and one dasyurid marsupials using histological sections was studied. Only the ventral, acromial portion of the scapular spine, which originates from the anterior margin of the scapular blade, is preformed in cartilage. The major dorsal portion is formed at a later stage by appositional bone, which expands from the perichondral ossification of the scapula into an intermuscular aponeurosis between the supra-and infraspinatus muscles. This intermuscular aponeurosis inserts more or less in the middle of the lateral surface of the developing scapula. Thus, the floor of the supraspinous fossa is already present at the beginning of scapular development, simultaneous with the infraspinous fossa. The portion of the scapular spine that is situated dorsal to the acromial process is hypothesized to be a neomorphic structure of therians. The dorsal portion of the scapular spine evolved as additional attachment for powerful supraspinatus and infraspinatus muscles meeting near the middle of the lateral scapula.