<unk>  was initially thought to be caused by mitochondrial dysfunction due to its symptoms and several reports of mitochondrial mutations. However, it has now been established that<unk>  is caused by endoplasmic reticulum dysfunction. left Two genetic forms have been described:<unk>  1 <unk> 1), and<unk>  2 <unk> 2).<unk> 1 The<unk> 1 or<unk> in gene provides instructions for making the<unk> in protein. The<unk> 1 gene is active in cells throughout the body, with strong activity in the heart, brain, lungs, inner ear, and pancreas. The pancreas provides enzymes that help digest food, and it also produces the hormone insulin. Insulin controls how much glucose (a type of sugar) is passed from the blood into cells for conversion to energy. Within cells,<unk> in is located in a structure called the endoplasmic reticulum. Among its many activities, the endoplasmic reticulum folds and modifies newly formed proteins so they have the correct 3-dimensional shape to function properly. The endoplasmic reticulum also helps transport proteins, fats, and other materials to specific sites within the cell or to the cell surface. The function of<unk> in is unknown. Based on its location in the endoplasmic reticulum, however, it may play a role in protein folding or cellular transport. In the pancreas,<unk> in may help fold a protein precursor of insulin (called proinsulin) into the mature hormone that controls blood glucose levels. Research findings also suggest that<unk> in may help maintain the correct cellular level of charged calcium atoms (calcium ions) by controlling how much is stored in the endoplasmic reticulum. In the inner ear,<unk> in may help maintain the proper levels of calcium ions or other charged particles that are essential for hearing. More than 30<unk> 1 mutations have been identified in individuals with a form of nonsyndromic deafness (hearing loss without related signs and symptoms affecting other parts of the body) called DFNA6. Individuals with DFNA6 deafness cannot hear low tones (low-frequency sounds), such as a tuba or the "m" in moon. DFNA6 hearing loss is unlike most forms of nonsyndromic deafness that affect high tones (high-frequency sounds), such as birds chirping, or all frequencies of sound. Most<unk> 1 mutations replace one of the protein building blocks (amino acids) used to make<unk> in with an incorrect amino acid. One mutation deletes an amino acid from<unk> in.<unk> 1 mutations probably alter the 3-dimensional shape of<unk> in, which could affect its function. Because the function of<unk> in is unknown, however, it is unclear how<unk> 1 mutations cause hearing loss. Some researchers suggest that altered<unk> in disturbs the balance of charged particles in the inner ear, which interferes with the hearing process. Other disorders - caused by mutations in the<unk> 1 gene Mutations in the<unk> 1 gene cause<unk> , which is also known by the acronym DIDMOAD. This syndrome is characterised by childhood-onset diabetes mellitus (DM), which results from the improper control of glucose due to the lack of insulin; a gradual loss of vision caused by optic atrophy (OA), in which the nerve that connects the eye to the brain wastes away; and deafness (D). This syndrome can sometimes cause diabetes insipidus (DI), a condition in which the kidneys cannot conserve water. Other complications that affect the bladder and nervous system may also occur. Researchers have identified more than 100<unk> 1 mutations that cause<unk> . Some mutations delete or insert DNA from the<unk> 1 gene. As a result, little or no<unk> in is present in cells. Other mutations replace one of the protein building blocks (amino acids) used to make<unk> in with an incorrect amino acid. These mutations appear to reduce<unk> in activity dramatically. Researchers suggest that the loss of<unk> in disrupts the production of insulin, which leads to poor glucose control and diabetes mellitus. It is unclear how<unk> 1 mutations lead to other features of<unk> .<unk> 2 The dysfunction of the CISD2 gene can cause<unk> 2.
Wolfram syndrome
Joubert syndrome
Kaufman oculocerebrofacial syndrome
Rett syndrome
De Barsy syndrome
TORCH syndrome
Foster Kennedy syndrome
Williams syndrome