Congenital Sucrase-Isomaltase Deficiency (CSID) Genetic Prevalence Study (GPS)

Inclusion Criteria:

- Must be 18 years of age or younger.

- A primary clinical diagnosis of chronic idiopathic diarrhea or chronic abdominal pain
for at least 4 weeks.

- English or Spanish speaking subjects and parent(s)/guardian only.

- Parental consent from one parent/guardian and also subject assent when appropriate
based on individual IRB requirements.

Exclusion Criteria:

- Any condition(s) or finding(s) that in the opinion of the principal investigator
suggests an alternative diagnosis for his/her gastrointestinal symptoms.

- Abdominal pain primarily related to constipation.

- Suspected gastrointestinal infectious disease.

- No current use of sacrosidase (Sucraid® Oral Solution).

- Known gastrointestinal disease such as celiac disease.

- Prior consumption of an investigational medication within the last 4 weeks.

- Antibiotics in the last 2 weeks, and no history of viral gastroenteritis within that
same period of time.

- Known Hepatitis B or C infection (positive HBsAg or HCV within 6 months of
enrollment) or Subject-Pugh Class C liver disease of any cause, HIV infection,
tuberculosis, Clostridia difficile co-infection, cancer or systemic infections.

- Severe neurologic impairment that would prevent them from reporting a history of
abdominal pain.

- Receiving or received biologic therapies (including infliximab, adalimumab,
natalizumab) within 3 months prior to or at enrollment.

- Present or past use of immune modulators therapy (e.g., azathioprine, 6MP,
methotrexate).

- Planned or previous abdominal surgery (e.g., bowel resection).

- Subjects with severe, uncontrolled systemic diseases.

- Presence of clinical alarm signs, including hypotension, anemia requiring blood
transfusions, altered mental status, or inability to tolerate food and/or fluids by
mouth.