Choline is an essential nutrient that is required for the synthesis of both acetylcholine, a neurotransmitter found in cholinergic nerve terminals, and phosphatidylcholine, a key component of cell membranes. Choline deficiencies are associated with defects in cell growth and have been implicated in disorders such as Alzheimer’s and Parkinson’s disease. The choline transporter-like protein family (CTL) are solute carriers that transport choline, a compound which is not able to permeate cells, across the cell membrane. CTL4, also known as SLC44A4 (Solute carrier family 44 member 4), is a multi-pass membrane protein which can fuse with Neu1, generating a CTL4-Neu1 transcript. This fusion is implicated in sialidosis, a disease characterized by improper lysosomal storage.