Contributor: Gordon K. Klintworth
GM1-gangliosidosis type II (juvenile GM1-gangliosidosis, OMIM # 230600)  is one variant of GM1-gangliosidosis. It  is caused by mutations in the GLB1 gene is allelic with GM1-gangliosidosis type I and GM1-gangliosidosis type III. This variant of  GM1-gangliosidosis mainly affects the central nervous system and presents later in life than GM1-gangliosidosis type. It is also milder than GM1-gangliosidosis type I with a slower progression, milder bony abnormalities and less severe neurological and psychomotor changes. In contrast to GM1-gangliosidosis type I coarse facial features, hepatosplenomegaly, visceromegaly, dysostosis multiplex, angiokeratomas, and stiff joints are absent.  Subtle skeletal abnormalities can be detected by careful roentgenographic examination. Slow neurological deterioration leads to death during the first decade.