Browsing Pathways

Lesch-Nyhan Syndrome is a syndrome identified through its neurological, behavioural metabolic impact. It is characterized by a mental deficit and self-mutilation, accompanied with an overproduction of uric acid. A mutation of the HPRT1 gene are responsible for this condition, as they cause the enzyme hypoxanthine phosphoribosyltransferase 1 to be present in extremely low levels or absent altogether. This causes an overproduction of uric acid as the purines are not recycled, but only broken down. This gene is also connected to dopamine production, which a lack of causes smooth muscle function to suffer, resulting in dystonia, ballismus and chorea. Patients are usually unable to walk, and the connection between a lack of hypoxanthine phosphoribosyltransferase 1 and the behavioural abnormalities associated with this condition are unknown.

Leukotriene C4 synthetase deficiency is caused by a defect in the enzyme leukotriene C4 synthetase (LTC4S). This enzyme catalyzes the synthesis of leukotriene C4 (LTC4) through conjugation of LTA4 with reduced glutathione (GSH), which is synthesized by glutathione synthetase. Leukotriene C4 and its receptor-binding metabolites LTD4 and LTE4 are cysteinyl leukotrienes that are potent lipid mediators of tissue inflammation. In general, leukotrienes are potent proinflammatory mediators synthesized from membrane-derived arachidonic acid after activation of certain granulocytes. A defect in LTC4 results in decreased concentrations of cysteinyl leukotrienes LTC4, LTD4 and LTE4 in plasma, spinal fluid and urine. Symptoms include early death, failure to thrive, motor retardation, microcephaly, and progressive neurological defect.

Very Long Chain Acyl CoA Dehydrogenase Deficiency (VLCADD) is a rare disorder that is inherited through an autosomal recessive trait, and prevents the body from properly metabolizing very long chain fatty acids. This disorder occurs in the mitochondria, where the metabolization of fatty acids takes place. Early-onset VLCADD patients usually begin to exhibit symptoms just days or weeks after birth. Hypoglycemia, lethargy and irritability are symptoms associated with this disorder. Patients will also be at risk for hypertrophic cardiomyopathy and other heart conditions from age two months to two years. It can be diagnosed through a research of family history and generally a urine analysis will reveal that the patient has reduced of absent ketone bodies. To help control acute episodes, treatment includes maintaining a high carbohydrate and low fat diet, and avoiding fasting for more than 12 hours.

Long Chain Acyl CoA Dehydrogenase Deficiency (LCADD) is a rare disorder that is inherited through an autosomal recessive trait, and prevents the body from properly metabolizing very long chain fatty acids. This disorder occurs in the mitochondria, where the metabolization of fatty acids takes place. Early-onset LCADD patients usually begin to exhibit symptoms just days or weeks after birth. Hypoglycemia, lethargy and irritability are symptoms associated with this disorder. Patients will also be at risk for hypertrophic cardiomyopathy and other heart conditions from age two months to two years. It can be diagnosed through a research of family history and generally a urine analysis will reveal that the patient has reduced of absent ketone bodies. To help control acute episodes, treatment includes maintaining a high carbohydrate and low fat diet, and avoiding fasting for more than 12 hours.

Long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency, which is also known LCHADD, is a rare inherited inborn error of metabolism (IEM) of long-chain fatty acid metabolism. The estimated birth prevalence of LCHADD is 1 in 62 000 in Northern European individuals. The worldwide birth prevalence is estimated at 1 in 250 000. MCADD is an autosomal recessive disorder associated with a mutation in the enzyme known as hydroxyacyl-CoA dehydrogenase (HADHA). HADHA catalyzes the last three steps of mitochondrial beta-oxidation of long chain fatty acids. HADHA converts medium- and long-chain 2-enoyl-CoA compounds into the corresponding 3-ketoacyl-CoA compounds when NAD is present, and acetyl-CoA when NAD and CoASH are present. Deficiencies in this enzyme prevent the body from converting certain fats to energy, particularly during periods without food (fasting). Signs and symptoms of LCHAD deficiency typically manifest during infancy or early childhood and can include feeding difficulties, hypoglycemia, hypotonia, lethargy, liver problems, and retinal abnormalities. During late childhood, people may experience muscle pain and peripheral neuropathy. LCHAD-deficiency individuals are also at risk for breathing difficulties, serious heart problems, coma, and sudden death. Fasting or illnesses (e.g. viral infections) can trigger related problems. LCHADD is associated with some pregnancy-specific disorders, including preeclampsia, HELLP syndrome (hemolysis, elevated liver enzymes, low platelets), hyperemesis gravidarum, acute fatty liver of pregnancy, and maternal floor infarction of the placenta.

Long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency, which is also known LCHADD, is a rare inherited inborn error of metabolism (IEM) of long-chain fatty acid metabolism. The estimated birth prevalence of LCHADD is 1 in 62 000 in Northern European individuals. The worldwide birth prevalence is estimated at 1 in 250 000. MCADD is an autosomal recessive disorder associated with a mutation in the enzyme known as hydroxyacyl-CoA dehydrogenase (HADHA). HADHA catalyzes the last three steps of mitochondrial beta-oxidation of long chain fatty acids. HADHA converts medium- and long-chain 2-enoyl-CoA compounds into the corresponding 3-ketoacyl-CoA compounds when NAD is present, and acetyl-CoA when NAD and CoASH are present. Deficiencies in this enzyme prevent the body from converting certain fats to energy, particularly during periods without food (fasting). Signs and symptoms of LCHAD deficiency typically manifest during infancy or early childhood and can include feeding difficulties, hypoglycemia, hypotonia, lethargy, liver problems, and retinal abnormalities. During late childhood, people may experience muscle pain and peripheral neuropathy. LCHAD-deficiency individuals are also at risk for breathing difficulties, serious heart problems, coma, and sudden death. Fasting or illnesses (e.g. viral infections) can trigger related problems. LCHADD is associated with some pregnancy-specific disorders, including preeclampsia, HELLP syndrome (hemolysis, elevated liver enzymes, low platelets), hyperemesis gravidarum, acute fatty liver of pregnancy, and maternal floor infarction of the placenta.

Lysinuric protein intolerance (Hyperdibasic aminoaciduria II; Dibasic aminoaciduria II; Hyperdibasic aminoaciduria II; LPI), also called hyperdibasic aminoaciduria type 2 or familial protein intolerance, is an autosomal recessive metabolic disorder affecting amino acid transport. LPI is caused by a defect in SLC7A7, Solute carrier family 7, a cationic amino acid transporter. A defect in this enzyme results in accumulation of ammmonia and reticulocytes in blood; glutamine in plasma, carnitine and ferritin in serum, and arginine, lysine and ornithine in urine. Symptoms include bone marrow abnormality, growth retardation, hyperammoniemia, mental retardation, pancreatitis, and seizures.

Lysinuric protein intolerance (LPI), also called hyperdibasic aminoaciduria, is a rare inborn error of metabolism (IEM) and autosomal recessive disorder of the kidney function pathway. It is caused by a mutation in the SLC7A7 gene which encodes the Y+L amino acid transporter 1 protein, which is involved in the uptake of amino acids, both with sodium for neutral amino acids, and without for dibasic amino acids. In this disorder, the amino acids lysin, arginine and ornithine, found in protein, cannot be broken down, which can cause problems in the systems that use these amino acids, such as the urea cycle. LPI is characterized by a shortage of lysine, arginine and ornithine within the body, causing elevated ammonia levels in the blood. Symptoms of the disorder include failure to thrive after weaning, nausea and vomiting following a meal containing large amounts of protein, as well as osteoporosis, and lung and kidney problems. Treatment with a protein restricted diet is effective, as well as prescription of medication to lower the levels of ammonia in the blood. It is estimated that the LPI affects 1 in 60,000 individuals in certain populations such as in Finland and Japan, and less frequently outside these populations.

Lysosomal Acid Lipase Deficiency, also known as Wolman disease, is predictably enough the result of a specific defect in lysosomal acid lipase. The defect results from a mutation on the 10th chromosome to the LIPA gene. Of interest is that the nature of the particular defect to the LIPA gene can result in two major, and distinct disorders. The first and more severe is the infantile-onset Wolman disease, whereas the other less severe disorder is late-onset cholesteryl ester storage diseas, also known as CESD. These two disorders are the product of mutations to different regions of the LIPA gene. Wolman disease is characterized by increased transaminases in serum, and increased cholesteryl esters and triglycerides in various tissues. Symptoms include anemia, diarrhea, failure to thrive, enlarged liver, malabsorption, steatorrhea and abdominal pain.

Lysosomal Acid Lipase Deficiency, also known as Wolman disease, is predictably enough the result of a specific defect in lysosomal acid lipase. The defect results from a mutation on the 10th chromosome to the LIPA gene. Of interest is that the nature of the particular defect to the LIPA gene can result in two major, and distinct disorders. The first and more severe is the infantile-onset Wolman disease, whereas the other less severe disorder is late-onset cholesteryl ester storage diseas, also known as CESD. These two disorders are the product of mutations to different regions of the LIPA gene. Wolman disease is characterized by increased transaminases in serum, and increased cholesteryl esters and triglycerides in various tissues. Symptoms include anemia, diarrhea, vomiting, failure to thrive, enlarged liver, malabsorption, steatorrhea and abdominal pain.