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The official name of this gene is “tripeptidyl peptidase I.”
TPP1 is the gene's official symbol. The TPP1 gene is also known by other names, listed below.
The TPP1 gene provides instructions for making an enzyme called tripeptidyl peptidase 1. This enzyme is produced as an inactive enzyme, called a proenzyme, which has an extra segment attached. This segment must be removed, followed by additional processing steps, for the enzyme to become active. The active tripeptidyl peptidase 1 enzyme is found in cell structures called lysosomes, which digest and recycle different types of molecules. This enzyme acts as a peptidase, which means that it breaks down protein fragments, known as peptides, into their individual building blocks (amino acids). Specifically, tripeptidyl peptidase 1 cuts (cleaves) peptides into groups of three amino acids.
At least 100 mutations in the TPP1 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. Most of the TPP1 gene mutations change single amino acids in tripeptidyl peptidase 1, resulting in a severe decrease in enzyme activity. One of two mutations, written as IV5-1G>C and R508X, causes nearly 90 percent of cases of late-infantile NCL worldwide.
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 TPP1 gene are involved in the buildup of lipopigments and the signs and symptoms of late-infantile NCL.
Cytogenetic Location: 11p15
Molecular Location on chromosome 11: base pairs 6,612,765 to 6,619,460
The TPP1 gene is located on the short (p) arm of chromosome 11 at position 15.
More precisely, the TPP1 gene is located from base pair 6,612,765 to base pair 6,619,460 on chromosome 11.
See How do geneticists indicate the location of a gene? (http://ghr.nlm.nih.gov/handbook/howgeneswork/genelocation) in the Handbook.
You and your healthcare professional may find the following resources about TPP1 helpful.
You may also be interested in these resources, which are designed for genetics professionals and researchers.
See How are genetic conditions and genes named? (http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/naming) in the Handbook.
acids ; cell ; ceroid ; enzyme ; epilepsy ; gene ; juvenile ; motor ; protease ; protein ; serine
You may find definitions for these and many other terms in the Genetics Home Reference Glossary (http://www.ghr.nlm.nih.gov/glossary).
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.