Therefore, a negative genetic test only means that the person does not carry one of the 37 SI gene variations that are known to be associated with CSID, but they may have an SI gene variation that has not yet been identified as one that can cause CSID. While the breath tests and genetic test have not been validated to be diagnostic for CSID, they may become important tests that help in identifying patients with CSID. As with all diagnoses, a diagnosis of CSID depends on combining a doctor’s clinical findings with results from objective tests. A physical examination, medical history, and other secondary tests, such as stool pH test for acidic stool, can aid in the diagnosis of CSID.If it is clinically inappropriate or difficult to perform a biopsy or if a CSID diagnosis is in doubt, a physician may suggest a two-week therapeutic trial with an enzyme replacement. If the patient shows a reduction of symptoms it is considered diagnostic for CSID. Treatment
The two ways to manage the gastrointestinal symptoms associated with CSID are:

Diet modification that eliminates or restricts the consumption of foods containing sucrose (table sugar) or starch sugarsThe use of enzyme replacement therapy to replace the action of the sucrase enzyme that is deficient. This medication requires a prescription from a doctor.
Interstitial lung disease (ILD), or diffuse parenchymal lung disease (DPLD), is a group of respiratory diseases affecting the interstitium (the tissue and space around the alveoli (air sacs)) of the lungs. It concerns alveolar epithelium, pulmonary capillary endothelium, basement membrane, and perivascular and perilymphatic tissues. It may occur when an injury to the lungs triggers an abnormal healing response. Ordinarily, the body generates just the right amount of tissue to repair damage, but in interstitial lung disease, the repair process is disrupted, and the tissue around the air sacs (alveoli) becomes scarred and thickened. This makes it more difficult for oxygen to pass into the bloodstream. The disease presents itself with the following symptoms: shortness of breath, nonproductive coughing, fatigue, and weight loss, which tend to develop slowly, over several months. The average rate of survival for someone with this disease is between three and five years. The term ILD is used to distinguish these diseases from obstructive airways diseases. There are specific types in children, known as childrens interstitial lung diseases. The acronym ChILD is sometimes used for this group of diseases.Prolonged ILD may result in pulmonary fibrosis, but this is not always the case. Idiopathic pulmonary fibrosis is interstitial lung disease for which no obvious cause can be identified (idiopathic) and is associated with typical findings both radiographic (basal and pleural-based fibrosis with honeycombing) and pathologic (temporally and spatially heterogeneous fibrosis, histopathologic honeycombing, and fibroblastic foci). In 2015, interstitial lung disease, together with pulmonary sarcoidosis, affected 1.9 million people.