This study is being conducted to better understand the natural course of GM1 gangliosidosis, GM2 gangliosidoses and Gaucher disease Type 2 (GD2). Information is planned to be gathered on at least 180 patients with GM1 gangliosidosis, GM2 gangliosidoses, and Gaucher Disease type 2. Retrospective data collection is planned for at least 150 deceased patients (Group A). Group B is for patients alive at the time of enrollment. In Group B it is planned to prospectively collect more comprehensive data from at least 30 patients. The purpose of this study is to collect relevant information for a adequate design of a potential subsequent research program in these diseases.

In this study no therapy is being offered.

Inclusion Criteria:

• Patient with either GM1 gangliosidosis, GM2 gangliosidoses (Tay-Sachs, Sandhoff, or AB Variant), or Gaucher Disease Type 2.
• Diagnosis confirmed by either biochemical (enzyme activity) or genetic testing, or both.
• Date of birth on or after 1 January 2000.
• Onset of first neurological symptom within 24 months of age.
• Informed consent of parent or legal guardian as required by local law.

This study will be conducted in hospitals/clinical centers managing pediatric patients with GM1 gangliosidosis, GM2 gangliosidoses, and/or Gaucher Disease type 2 across several countries in North America, South America, and Europe. In order to minimize the patient/data selection bias, the centers are asked to include all eligible patients from their center.