Biology of CLN5, a Subtype of Batten Disease

How CLN5 Disease Affects the Body

CLN5 disease affects children both cognitively and physically. Symptoms of the disease may include:

Science Behind CLN5 Disease

The underlying cause of CLN5 disease is found in an individual’s genetic code. In humans, each cell contains 23 pairs of chromosomes for a total of 46: 23 from their mother and 23 from their father. The first 22 pairs of chromosomes are autosomesAny chromosome in a cell that is not an X or Y sex chromosome. The average person has 22 pairs of autosomes (44 autosomes in total) in each cell that define the genetic make-up, or DNA, of the being. These chromosomes store thousands of genes and they are inherited from the beings’ parents. In addition to the 22 pairs of autosomes (44 total), beings also have one pair (2 total) sex chromosomes (X and Y in a male, and X and X in a female)., and they look the same in both males and females. The 23^rd pair are sex chromosomes, which are different between males and females. Females have two copies of the X chromosomes (XX) and males have one X and one Y chromosome (XY). A variantA variant is a change in DNA. A variant may or may not cause disease. The following modifiers describe the variant: (i) pathogenic, (ii) likely pathogenic, (iii) uncertain significance, (iv) likely benign, or (v) benign depending on whether or not the variant causes disease. For example, a “pathogenic variant” may cause disease. The term “variant” has replaced the term “mutation.” in a gene on one of the first 22 autosomes can lead to an autosomalInheritance characteristic where a gene is located on a numbered, non-sex chromosome. These are found on one of the 22 pairs of (44 total) autosomal chromosomes in a human body where DNA is stored. This is one of several ways that a trait, disorder, or disease can be passed down through families. These chromosomes are not the sex (X or Y) chromosomes. disease.

Autosomal recessive is one of several ways that a disorder or disease is passed down through families. An autosomal recessive disorder occurs when a child inherits two copies of a mutated gene, one from the mother and one from the father. The biological parents, known as carriers, each carry only one copy of the mutated gene, and usually do not show symptoms of the disease.

CLN5 disease is inherited in an autosomal recessive pattern, meaning both copies of the CLN5 gene variant (one from each parent, or carrier) must be present for the child to be diagnosed with CLN5 disease.

Healthy CLN5 Gene

A healthy CLN5 gene provides the body with instructions for building the CLN5 protein. Although the exact function of the protein is unknown, it is thought to play a role in lysosomal function. In lysosomesSpecialized vesicles within cells that digest large molecules, breaking down excess waste products of the cell with the help of enzymes. Lysosomes may also be used to destroy invading viruses and bacteria., waste is recycled or disposed of properly, resulting in normal cellular function.

CLN5 Variant

People with CLN5 disease have a variant on the CLN5 gene, located on chromosome 12. When there is a variant or mutationA mutation is any inherited genetic change. The term “mutation” is being replaced by the term “variant.” in the CLN5 gene, the body creates a non-functional CLN5 protein, resulting in lysosomal dysfunction. The lysosome, when unable to function properly, causes a toxic accumulation of material in cells throughout the body.

Although the CLN5 protein is expressed throughout the body, nerve cells seem to be the most impacted, leading to the central nervous system-related signs and symptoms seen in patients who have CLN5.

Sources:

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