A New Retrospective Natural History Study of Mucolipidosis Type IV
The primary objectives of the study are: to describe the characteristics of the current international MLIV population; to define the median age at which patients with MLIV achieve or lose developmental milestones; to define the natural history of MLIV for the Gross Motor Function Classification System (GMFCS) (Morris and Bartlett, 2004) and the MLIV specific scale and test the validity of retrospectively applying these scales to medical record data; to define the rate of visual decline in patients with MLIV.
• Patient of any age or gender with a diagnosis of MLIV confirmed through 1) genetic testing and identification of homozygous MCOLN1 allele variants known to be pathogenic, or 2) clinical characteristics consistent with MLIV and one of the following: a) electron microscopy of fibroblasts or other patient cells demonstrating abnormal lysosomal accumulations consistent with MLIV, or b) elevated gastrin levels (pathognomonic for MLIV in the setting of a neurodevelopmental disorder). Potential participants or guardians must be able to provide informed consent (patient assent is not applicable to the MLIV population).