GJB3 Gene

Definition:Gap junction protein, beta 3, 31kDa.

Official Symbol:GJB3

 Chromosome:1

 Location : 1p34

Gene Size:  5178 bp (35,019,377 to 35,024,554)


No Exons:

Description:

Gene is a member of the connexin gene family. The encoded protein is a component of gap junctions, which are composed of arrays of intercellular channels that provide a route for the diffusion of low molecular weight materials from cell to cell.Connexin 31 is found in several different tissues throughout the body, including the skin, the inner ear, and the nerve that connects the inner ear with the brain (the auditory nerve). Connexin 31 plays a role in the growth and maturation of the outermost layer of skin (the epidermis). The presence of this protein in the inner ear and auditory nerve suggests that it may be involved in hearing. Hearing requires the conversion of sound waves to electrical nerve impulses, which travel along the auditory nerve to the brain. The exact role of connexin 31 in the inner ear and auditory nerve is unclear.

Disease :

Mutations in this gene can cause non-syndromic deafness or erythrokeratodermia variabilis, a skin disorder. Alternative splicing results in multiple transcript variants encoding the same protein.

nonsyndromic deafness

    Researchers have identified a few GJB3 mutations in people with a form of nonsyndromic deafness (hearing loss without related signs and symptoms affecting other parts of the body) called DFNA2. DFNA2 deafness is inherited in an autosomal dominant manner, which means that one copy of the GJB3 gene in each cell is altered. A few GJB3 mutations have also been identified in people with autosomal recessive nonsyndromic deafness. This type of inheritance means that two copies of the GJB3 gene in each cell are altered. It is unclear, however, whether GJB3 mutations are the direct cause of hearing loss in individuals with either of these types of deafness.

    GJB3 mutations related to hearing loss alter the sequence of protein building blocks (amino acids) in connexin 31. Some mutations lead to missing amino acids in connexin 31, and other mutations replace one amino acid with an incorrect amino acid. These changes likely alter the 3-dimensional shape or size of connexin 31, which could disrupt the assembly or function of gap junctions. It is unclear how GJB3 mutations contribute to hearing loss.

GBA Gene

Defintion:Glucosidase, beta; acid (includes glucosylceramidase) also known as GCB; GBA1; GLUC


official Symbol:GBA


Chromosome:1

Location : 1q21


Gene Size: 10246 bp (153470867..153481112) complement



No Exons:12


Description:

This gene encodes a lysosomal membrane protein that cleaves the beta-glucosidic linkage of glycosylceramide, an intermediate in glycolipid metabolism.This enzyme is active in lysosomes, which are structures inside cells that act as recycling centers. Lysosomes use digestive enzymes to break down toxic substances, digest bacteria that invade the cell, and recycle worn-out cell components. Based on these functions, enzymes in the lysosome are sometimes called housekeeping enzymes. Beta-glucocerebrosidase is a housekeeping enzyme that helps break down a large molecule called glucocerebroside into a sugar (glucose) and a simpler fat molecule (ceramide).

Disease :

Mutations in this gene cause Gaucher disease, a lysosomal storage disease characterized by an accumulation of glucocerebrosides,It is found that more than 200 mutations occurs in GBA gene.Which causes Gaucher Disease,Most of the GBA mutations responsible for Gaucher disease change a single protein building block (amino acid) in beta-glucocerebrosidase, altering the structure of the enzyme and preventing it from working normally. Other mutations delete or insert genetic material in the GBA gene or lead to the production of an abnormally short, nonfunctional version of the enzyme.

Growing evidence suggests an association between GBA mutations and Parkinson disease or Parkinson-like disorders that affect movement and balance (parkinsonism). People with Gaucher disease have mutations in both copies of the GBA gene in each cell, while those with a mutation in just one copy of the gene are called carriers. Some studies suggest that people with Gaucher disease and GBA mutation carriers have an increased risk of developing Parkinson disease or parkinsonism.

Symptoms of Parkinson disease and parkinsonism result from the loss of nerve cells that produce dopamine. Dopamine is a chemical messenger that transmits signals within the brain to produce smooth physical movements. It remains unclear how GBA mutations lead to these disorders. Researchers speculate that GBA mutations may contribute to the faulty breakdown of toxic substances in nerve cells by impairing the function of lysosomes, or mutations may enhance the formation of abnormal protein deposits. As a result, toxic substances or protein deposits could accumulate and kill dopamine-producing nerve cells, leading to abnormal movements and balance problems.

GALE Gene

Defintion: The Official name of GALE  UDP-galactose-4-epimerase

Chromosome:1

Loaction :1p36-p35

Gene Size: 5206 bp( 23994676 to 23999881)


No Exons: 12

Description:
The GALE gene provides instructions for making an enzyme called UDP-galactose-4-epimerase. This enzyme enables the body to process a simple sugar called galactose, which is present in small amounts in many foods. Galactose is primarily part of a larger sugar called lactose,


Disease :
Mutations in this gene result in epimerase-deficiency galactosemia, also referred to as galactosemia type 3, More than 20 mutations in the GALE gene have been identified in people with a form of galactosemia known as type III or galactose epimerase deficiency,a disease characterized by liver damage, early-onset cataracts, deafness and mental retardation, with symptoms ranging from mild ('peripheral' form) to severe ('generalized' form). Multiple alternatively spliced transcripts encoding the same protein have been identified.