GPHN and glycine encephalopathy: Other relatively frequent disorders include biotinidase deficiency (mutation in the BTD gene, autosomal recessive inheritance), nonketotic hyperglycinemia (mutation in the GLDC, AMT, GCSH genes; autosomal recessive mutations), molybdenum cofactor and sulfite oxidase deficiency (mutations in the MOCS1 and MOCS2 genes, as well as in the GPHN gene responsible for cofactor deficiency or in the SUOX gene responsible for oxidase deficiency) [31,37,43,46].