Hypomyelinating leukodystrophy 16, also known as HLD16, is a rare genetic disorder that affects the development of myelin, the protective covering around nerve fibers in the brain. HLD16 is caused by a mutation in the gene TMEM106B. We genetically engineered mice in a way that they have the same mutation in TMEM106B that is found in human patients. We plan to investigate these mice to understand the disease and how the mutation in this gene, whose function is yet unknown, leads to this rare disease. This will help to develop future therapies and understand the function of TMEM106B in myelination.