Cystathionine beta synthase deficiency and brain edema associated with methionine excess under betaine supplementation: Four new cases and a review of the evidence oleh Bernd C. Schwahn, Thomas Scheffner, Hedwig Stepman, Peter Verloo, Anibh M Das, Janice Fletcher, Henk J Blom, Jean‐Francois Benoist, Bruce A. Barshop, Jaime J. Barea, Annette Feigenbaum