ceroid-lipofuscinosis, neuronal 5
The CLN5 gene provides instructions for making a protein whose function is unknown. When produced, the CLN5 protein has extra protein segments attached and is inactive. This form is called a preprotein. For the CLN5 protein to become active, the additional segments must be removed from the preprotein, followed by additional processing steps. The active CLN5 protein is found in cell compartments called lysosomes, which digest and recycle different types of molecules.
Genetics Home Reference provides information about infantile neuronal ceroid lipofuscinosis.
Genetics Home Reference provides information about juvenile Batten disease.
More than 20 mutations in the CLN5 gene have been found to cause late-infantile neuronal ceroid lipofuscinosis (NCL). This condition impairs motor and mental development beginning in early childhood, causing movement disorders and a decline in intellectual function. In addition, affected children often develop recurrent seizures (epilepsy) and vision impairment. One mutation (known as Finmajor) is responsible for almost all cases of late-infantile NCL caused by CLN5 gene mutations in people of Finnish descent. The Finmajor mutation replaces the protein building block (amino acid) tyrosine with a signal to stop protein production prematurely (written as Y392X). This mutation leads to an unstable protein that is quickly broken down. Other mutations interfere with processing of the immature protein or its transport to the lysosome.
Fatty substances called lipopigments accumulate in the lysosomes of people with late-infantile NCL. These accumulations can result in cell dysfunction and eventually cause cell death, especially in brain cells, which are particularly vulnerable to damage caused by lipopigments. However, it is unclear how mutations in the CLN5 gene are involved in the buildup of lipopigments and the signs and symptoms of late-infantile NCL.
- ceroid-lipofuscinosis neuronal protein 5