GSD9 has three liver sub-types: a, b, c and one extremely rare muscle sub-type: d.
GSD9 is one of the least severe forms of GSD. In most individuals apart from liver enlargement there are few other problems. There is usually no tendency to low blood sugar, the liver becomes smaller with age and children grow normally.
Most cases of GSD9 are from X-linked inheritance and thus affect males only. However, GSD9 can be inherited in an autosomal recessive manner, in which case both male and female children of two carriers have a 25% chance of having the disease.
See the panel in the Diagnosis and Follow up section.