PYGL and disorder of glycogen metabolism: In the present study, 18 different heterozygous candidate mutations (9 novel and 9 reported) were identified in 12 Chinese GSD families: 7 families carrying GAA mutations (7/12, 58.3%), 2 carrying AGL mutations (2/12, 16.7%), 1 carrying PYGL mutation (1/12, 8.3%), and 2 carrying PHKA2 mutations (2/12, 16.7%).