bowang0911/MedQuAD huggingface dataset:
Bradyopsia can be caused by mutations in the RGS9 gene or in the RGS9BP gene (which is also known as R9AP). These genes provide instructions for making proteins that are necessary for normal vision. The proteins are found in light-detecting cells in the eye called photoreceptors. When light enters the eye, it stimulates specialized pigments in these cells. This stimulation triggers a series of chemical reactions that produce an electrical signal, which is interpreted by the brain as vision. Once photoreceptors have been stimulated by light, they must return to their resting state before they can be stimulated again. The RGS9 and RGS9BP proteins play an essential role in returning photoreceptors to their resting state quickly after light exposure.  Mutations in either the RGS9 or RGS9BP gene prevent photoreceptors from recovering quickly after responding to light. Normally they return to their resting state in a fraction of a second, but in people with mutations in one of these genes, it can take ten seconds or longer. During that time, the photoreceptors cannot respond to light. This delay causes temporary blindness in response to changing light conditions and interferes with seeing small objects when they are in motion.  In some people with bradyopsia, no mutations in the RGS9 or RGS9BP gene have been found. The cause of the condition in these individuals is unknown.
These resources address the diagnosis or management of bradyopsia:  - Children's Hospital of Pittsburgh: Electroretinogram  - Genetic Testing Registry: Prolonged electroretinal response suppression  - MedlinePlus Encyclopedia: Electroretinography  - Prevent Blindness: Living Well with Low Vision   These resources from MedlinePlus offer information about the diagnosis and management of various health conditions:  - Diagnostic Tests  - Drug Therapy  - Surgery and Rehabilitation  - Genetic Counseling   - Palliative Care
Stargardt macular degeneration is a genetic eye disorder that causes progressive vision loss. This disorder affects the retina, the specialized light-sensitive tissue that lines the back of the eye. Specifically, Stargardt macular degeneration affects a small area near the center of the retina called the macula. The macula is responsible for sharp central vision, which is needed for detailed tasks such as reading, driving, and recognizing faces. In most people with Stargardt macular degeneration, a fatty yellow pigment (lipofuscin) builds up in cells underlying the macula. Over time, the abnormal accumulation of this substance can damage cells that are critical for clear central vision. In addition to central vision loss, people with Stargardt macular degeneration have problems with night vision that can make it difficult to navigate in low light. Some affected individuals also have impaired color vision. The signs and symptoms of Stargardt macular degeneration typically appear in late childhood to early adulthood and worsen over time.
In most cases, Stargardt macular degeneration is caused by mutations in the ABCA4 gene. Less often, mutations in the ELOVL4 gene cause this condition. The ABCA4 and ELOVL4 genes provide instructions for making proteins that are found in light-sensing (photoreceptor) cells in the retina.  The ABCA4 protein transports potentially toxic substances out of photoreceptor cells. These substances form after phototransduction, the process by which light entering the eye is converted into electrical signals that are transmitted to the brain. Mutations in the ABCA4 gene prevent the ABCA4 protein from removing toxic byproducts from photoreceptor cells. These toxic substances build up and form lipofuscin in the photoreceptor cells and the surrounding cells of the retina, eventually causing cell death. Loss of cells in the retina causes the progressive vision loss characteristic of Stargardt macular degeneration.  The ELOVL4 protein plays a role in making a group of fats called very long-chain fatty acids. The ELOVL4 protein is primarily active (expressed) in the retina, but is also expressed in the brain and skin. The function of very long-chain fatty acids within the retina is unknown. Mutations in the ELOVL4 gene lead to the formation of ELOVL4 protein clumps (aggregates) that build up and may interfere with retinal cell functions, ultimately leading to cell death.
Stargardt macular degeneration can have different inheritance patterns.  When mutations in the ABCA4 gene cause this condition, it is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.  When this condition is caused by mutations in the ELOVL4 gene, it is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.
These resources address the diagnosis or management of Stargardt macular degeneration:  - Genetic Testing Registry: Stargardt Disease 3  - Genetic Testing Registry: Stargardt disease 1  - Genetic Testing Registry: Stargardt disease 4   These resources from MedlinePlus offer information about the diagnosis and management of various health conditions:  - Diagnostic Tests  - Drug Therapy  - Surgery and Rehabilitation  - Genetic Counseling   - Palliative Care
Essential pentosuria is caused by mutations in the DCXR gene. This gene provides instructions for making a protein called dicarbonyl/L-xylulose reductase (DCXR), which plays multiple roles in the body. One of its functions is to perform a chemical reaction that converts a sugar called L-xylulose to a molecule called xylitol. This reaction is one step in a process by which the body can use sugars for energy.  DCXR gene mutations lead to the production of altered DCXR proteins that are quickly broken down. Without this protein, L-xylulose is not converted to xylitol, and the excess sugar is released in the urine.  While essential pentosuria is caused by genetic mutations, some people develop a non-inherited form of pentosuria if they eat excessive amounts of fruits high in L-xylulose or another pentose called L-arabinose. This form of the condition, which disappears if the diet is changed, is referred to as alimentary pentosuria. Studies show that some drugs can also cause a form of temporary pentosuria called drug-induced pentosuria. These non-inherited forms of the condition also do not cause any health problems.
Leptin receptor deficiency is a condition that causes severe obesity beginning in the first few months of life. Affected individuals are of normal weight at birth, but they are constantly hungry and quickly gain weight. The extreme hunger leads to chronic excessive eating (hyperphagia) and obesity. Beginning in early childhood, affected individuals develop abnormal eating behaviors such as fighting with other children over food, hoarding food, and eating in secret.  People with leptin receptor deficiency also have hypogonadotropic hypogonadism, which is a condition caused by reduced production of hormones that direct sexual development. Affected individuals experience delayed puberty or do not go through puberty, and may be unable to conceive children (infertile).
Leptin receptor deficiency is caused by mutations in the LEPR gene. This gene provides instructions for making a protein called the leptin receptor, which is involved in the regulation of body weight. The leptin receptor protein is found on the surface of cells in many organs and tissues of the body including a part of the brain called the hypothalamus. The hypothalamus controls hunger and thirst as well as other functions such as sleep, moods, and body temperature. It also regulates the release of many hormones that have functions throughout the body.  The leptin receptor is turned on (activated) by a hormone called leptin that attaches (binds) to the receptor, fitting into it like a key into a lock. Normally, the body's fat cells release leptin in proportion to their size. As fat cells become larger, they produce more leptin. This rise in leptin indicates that fat stores are increasing. In the hypothalamus, the binding of leptin to its receptor triggers a series of chemical signals that affect hunger and help produce a feeling of fullness (satiety).  LEPR gene mutations that cause leptin receptor deficiency prevent the receptor from responding to leptin, leading to the excessive hunger and weight gain associated with this disorder. Because hypogonadotropic hypogonadism occurs in leptin receptor deficiency, researchers suggest that leptin receptor signaling is also involved in regulating the body's response to hormones that control sexual development, and that this response is affected by LEPR gene mutations. However, the mechanism of this effect is unknown.  Leptin receptor deficiency is a rare cause of obesity. Researchers are studying the factors involved in more common forms of obesity.
These resources address the diagnosis or management of leptin receptor deficiency:  - Eunice Kennedy Shriver National Institute of Child Health and Human Development: How Are Obesity and Overweight Diagnosed?  - Genetic Testing Registry: Leptin receptor deficiency  - Genetics of Obesity Study  - National Heart, Lung, and Blood Institute: How Are Overweight and Obesity Treated?   These resources from MedlinePlus offer information about the diagnosis and management of various health conditions:  - Diagnostic Tests  - Drug Therapy  - Surgery and Rehabilitation  - Genetic Counseling   - Palliative Care
Loeys-Dietz syndrome is a disorder that affects the connective tissue in many parts of the body. Connective tissue provides strength and flexibility to structures such as bones, ligaments, muscles, and blood vessels.  There are four types of Loeys-Dietz syndrome, labelled types I through IV, which are distinguished by their genetic cause. Regardless of the type, signs and symptoms of Loeys-Dietz syndrome can become apparent anytime in childhood or adulthood, and the severity is variable.  Loeys-Dietz syndrome is characterized by enlargement of the aorta, which is the large blood vessel that distributes blood from the heart to the rest of the body. The aorta can weaken and stretch, causing a bulge in the blood vessel wall (an aneurysm). Stretching of the aorta may also lead to a sudden tearing of the layers in the aorta wall (aortic dissection). People with Loeys-Dietz syndrome can also have aneurysms or dissections in arteries throughout the body and have arteries with abnormal twists and turns (arterial tortuosity).  Individuals with Loeys-Dietz syndrome often have skeletal problems including premature fusion of the skull bones (craniosynostosis), an abnormal side-to-side curvature of the spine (scoliosis), either a sunken chest (pectus excavatum) or a protruding chest (pectus carinatum), an inward- and upward-turning foot (clubfoot), flat feet (pes planus), or elongated limbs with joint deformities called contractures that restrict the movement of certain joints. Degeneration of the discs that separate the bones of the spine (vertebrae), often affecting the neck, is a common finding. Some affected individuals have prominent joint inflammation (osteoarthritis) that commonly affects the knees and the joints of the hands, wrists, and spine.  People with Loeys-Dietz syndrome may bruise easily and develop abnormal scars after wound healing. The skin is frequently described as translucent, often with stretch marks (striae) and visible underlying veins. Other characteristic features include widely spaced eyes (hypertelorism), a split in the soft flap of tissue that hangs from the back of the mouth (bifid uvula), and an opening in the roof of the mouth (cleft palate).  Individuals with Loeys-Dietz syndrome frequently develop immune system-related problems such as food allergies, asthma, or inflammatory disorders such as eczema or inflammatory bowel disease.
The four types of Loeys-Dietz syndrome are distinguished by their genetic cause: mutations in the TGFBR1 gene cause type I, mutations in the TGFBR2 gene cause type II, mutations in the SMAD3 gene cause type III, and mutations in the TGFB2 gene cause type IV. These four genes play a role in cell signaling that promotes growth and development of the body's tissues. This signaling pathway also helps with bone and blood vessel development and plays a part in the formation of the extracellular matrix, an intricate lattice of proteins and other molecules that forms in the spaces between cells.  Mutations in the TGFBR1, TGFBR2, TGFB2, and SMAD3 genes result in the production of proteins with little or no function. Even though these proteins have severely reduced function, cell signaling occurs at an even greater intensity than normal. Researchers speculate that the activity of proteins in this signaling pathway is increased to compensate for the protein whose function is reduced; however, the exact mechanism responsible for the increase in signaling is unclear. The overactive signaling pathway disrupts the development of connective tissue, the extracellular matrix, and various body systems, leading to the varied signs and symptoms of Loeys-Dietz syndrome.
These resources address the diagnosis or management of Loeys-Dietz syndrome:  - Gene Review: Gene Review: Loeys-Dietz Syndrome  - Genetic Testing Registry: Loeys-Dietz syndrome  - Genetic Testing Registry: Loeys-Dietz syndrome 1  - Genetic Testing Registry: Loeys-Dietz syndrome 2  - Genetic Testing Registry: Loeys-Dietz syndrome 3  - Genetic Testing Registry: Loeys-Dietz syndrome 4  - Johns Hopkins Medicine: Diagnosis of Craniosynostosis  - MedlinePlus Encyclopedia: Aortic Dissection  - National Heart Lung and Blood Institute: How Is an Aneurysm Treated?   These resources from MedlinePlus offer information about the diagnosis and management of various health conditions:  - Diagnostic Tests  - Drug Therapy  - Surgery and Rehabilitation  - Genetic Counseling   - Palliative Care
Nephrogenic diabetes insipidus is a disorder of water balance. The body normally balances fluid intake with the excretion of fluid in urine. However, people with nephrogenic diabetes insipidus produce too much urine (polyuria), which causes them to be excessively thirsty (polydipsia). Affected individuals can quickly become dehydrated if they do not drink enough water, especially in hot weather or when they are sick.  Nephrogenic diabetes insipidus can be either acquired or hereditary. The acquired form is brought on by certain drugs and chronic diseases and can occur at any time during life. The hereditary form is caused by genetic mutations, and its signs and symptoms usually become apparent within the first few months of life.  Infants with hereditary nephrogenic diabetes insipidus may eat poorly and fail to gain weight and grow at the expected rate (failure to thrive). They may also be irritable and experience fevers, diarrhea, and vomiting. Recurrent episodes of dehydration can lead to slow growth and delayed development. If the condition is not well-managed, over time it can damage the bladder and kidneys leading to pain, infections, and kidney failure. With appropriate treatment, affected individuals usually have few complications and a normal lifespan.  Nephrogenic diabetes insipidus should not be confused with diabetes mellitus, which is much more common. Diabetes mellitus is characterized by high blood sugar levels resulting from a shortage of the hormone insulin or an insensitivity to this hormone. Although nephrogenic diabetes insipidus and diabetes mellitus have some features in common, they are separate disorders with different causes.
The hereditary form of nephrogenic diabetes insipidus can be caused by mutations in at least two genes. About 90 percent of all cases of hereditary nephrogenic diabetes insipidus result from mutations in the AVPR2 gene. Most of the remaining 10 percent of cases are caused by mutations in the AQP2 gene. Both of these genes provide instructions for making proteins that help determine how much water is excreted in urine.  The acquired form of nephrogenic diabetes insipidus can result from chronic kidney disease, certain medications (such as lithium), low levels of potassium in the blood (hypokalemia), high levels of calcium in the blood (hypercalcemia), or an obstruction of the urinary tract.  The kidneys filter the blood to remove waste and excess fluid, which are stored in the bladder as urine. The balance between fluid intake and urine excretion is controlled by a hormone called vasopressin or antidiuretic hormone (ADH). ADH directs the kidneys to concentrate urine by reabsorbing some of the water into the bloodstream. Normally, when a person's fluid intake is low or when a lot of fluid is lost (for example, through sweating), increased levels of ADH in the blood tell the kidneys to make less urine. When fluid intake is adequate, lower levels of ADH tell the kidneys to make more urine.  Mutations in the AVPR2 or AQP2 genes prevent the kidneys from responding to signals from ADH. Chronic kidney disease, certain drugs, and other factors can also impair the kidneys' ability to respond to this hormone. As a result, the kidneys do not reabsorb water as they should, and the body makes excessive amounts of urine. These problems with water balance are characteristic of nephrogenic diabetes insipidus.
When nephrogenic diabetes insipidus results from mutations in the AVPR2 gene, the condition has an X-linked recessive pattern of inheritance. The AVPR2 gene is located on the X chromosome, which is one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation usually has to occur in both copies of the gene to cause the disorder. However, some females who carry a single mutated copy of the AVPR2 gene have features of nephrogenic diabetes insipidus, including polyuria and polydipsia. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.  When nephrogenic diabetes insipidus is caused by mutations in the AQP2 gene, it can have either an autosomal recessive or, less commonly, an autosomal dominant pattern of inheritance. In autosomal recessive inheritance, both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. In autosomal dominant inheritance, one mutated copy of the AQP2 gene in each cell is sufficient to cause the disorder.
These resources address the diagnosis or management of nephrogenic diabetes insipidus:  - Gene Review: Gene Review: Nephrogenic Diabetes Insipidus  - Genetic Testing Registry: Nephrogenic diabetes insipidus  - Genetic Testing Registry: Nephrogenic diabetes insipidus, X-linked  - Genetic Testing Registry: Nephrogenic diabetes insipidus, autosomal  - MedlinePlus Encyclopedia: ADH  - MedlinePlus Encyclopedia: Diabetes Insipidus - Nephrogenic   These resources from MedlinePlus offer information about the diagnosis and management of various health conditions:  - Diagnostic Tests  - Drug Therapy  - Surgery and Rehabilitation  - Genetic Counseling   - Palliative Care
Leukoencephalopathy with brainstem and spinal cord involvement and lactate elevation (commonly referred to as LBSL) is a progressive disorder that affects the brain and spinal cord. Leukoencephalopathy refers to abnormalities in the white matter of the brain, which is tissue containing nerve cell fibers (axons) that transmit nerve impulses.  Most affected individuals begin to develop movement problems during childhood or adolescence. However, in some individuals, these problems do not develop until adulthood. People with LBSL have abnormal muscle stiffness (spasticity) and difficulty with coordinating movements (ataxia). In addition, affected individuals lose the ability to sense the position of their limbs or vibrations with their limbs. These movement and sensation problems affect the legs more than the arms, making walking difficult. Most affected individuals eventually require wheelchair assistance, sometimes as early as their teens, although the age varies.  People with LBSL can have other signs and symptoms of the condition. Some affected individuals develop recurrent seizures (epilepsy), speech difficulties (dysarthria), learning problems, or mild deterioration of mental functioning. Some people with this disorder are particularly vulnerable to severe complications following minor head trauma, which may trigger a loss of consciousness, other reversible neurological problems, or fever.  Distinct changes in the brains of people with LBSL can be seen using magnetic resonance imaging (MRI). These characteristic abnormalities typically involve particular parts of the white matter of the brain and specific regions (called tracts) within the brain stem and spinal cord, especially the pyramidal tract and the dorsal column. In addition, most affected individuals have a high level of a substance called lactate in the white matter of the brain, which is identified using another test called magnetic resonance spectroscopy (MRS).
LBSL is caused by mutations in the DARS2 gene, which provides instructions for making an enzyme called mitochondrial aspartyl-tRNA synthetase. This enzyme is important in the production (synthesis) of proteins in cellular structures called mitochondria, the energy-producing centers in cells. While most protein synthesis occurs in the fluid surrounding the nucleus (cytoplasm), some proteins are synthesized in the mitochondria.  During protein synthesis, in either the mitochondria or the cytoplasm, building blocks (amino acids) are connected together in a specific order, creating a chain of amino acids that forms the protein. Mitochondrial aspartyl-tRNA synthetase plays a role in adding the amino acid aspartic acid at the proper place in mitochondrial proteins.  Mutations in the DARS2 gene result in decreased mitochondrial aspartyl-tRNA synthetase enzyme activity, which hinders the addition of aspartic acid to mitochondrial proteins. It is unclear how the gene mutations lead to the signs and symptoms of LBSL. Researchers do not understand why reduced activity of mitochondrial aspartyl-tRNA synthetase specifically affects certain parts of the brain and spinal cord.
LBSL is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. In this condition, each copy of the gene carries a different mutation (compound heterozygous mutations). An affected individual never has the same mutation in both copies of the gene (a homozygous mutation). The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.
These resources address the diagnosis or management of LBSL:  - Gene Review: Gene Review: Leukoencephalopathy with Brain Stem and Spinal Cord Involvement and Lactate Elevation  - Genetic Testing Registry: Leukoencephalopathy with Brainstem and Spinal Cord Involvement and Lactate Elevation   These resources from MedlinePlus offer information about the diagnosis and management of various health conditions:  - Diagnostic Tests  - Drug Therapy  - Surgery and Rehabilitation  - Genetic Counseling   - Palliative Care