Sialidosis type 1 and 3: A rare inherited biochemical disorder involving the deficiency of an enzyme (alpha-N-acetylneuraminidase) which results in the harmful accumulation of certain chemicals (sialyloligosaccharides and sialylglycopeptides) in various body tissues.
Sialuria, French type: A rare disorder characterized by the excretion of large amounts of sialic acid in the urine due to a metabolic error.
Sickle cell anemia is a disease in which the body produces abnormally shaped red blood cells that have a crescent or sickle shape. These cells do not last as long as normal, round, red blood cells, which leads to anemia (low number of red blood cells). The sickle cells also get stuck in blood vessels, blocking blood flow. Signs and symptoms of sickle cell disease usually begin in early childhood and may include anemia, repeated infections, and periodic episodes of pain (called crises). This condition is caused by mutations in the HBB gene and is inherited in an autosomal recessive pattern. Treatment typically focuses on controlling symptoms and may include pain medicines during crises; hydroxyurea to reduce the number of pain episodes; antibiotics and vaccines to prevent bacterial infections; and blood transfusions
Siderius type X-linked mental retardation syndrome: A rare inherited form of mental retardation involving a defect on chromosome Xp11.2. The symptoms are evident in males but females may be carriers.
Sideroblastic anemia, autosomal: An inherited form of anemia where an enzyme deficiency prevents red blood cells from using iron properly. The red blood cells become overloaded with iron which impairs the blood's ability to carry oxygen.
Siderosis: Abnormal deposits of iron in body tissues. Symptoms will depend on which tissues the iron is deposited in.
Siegler-Brewer-Carey syndrome: A very rare syndrome characterized mainly by cataracts, ear infections, poor absorption by the intestines, respiratory infections and failure to thrive.
Silicosiderosis: A lung disorder caused by breathing in dust containing iron and silica.
Alternative Names: Acute silicosis; Chronic silicosis; Accelerated silicosis; Progressive massive fibrosis; Conglomerate silicosis. Silicosis is a respiratory disease caused by inhaling silica dust.
Sillence syndrome: An extremely rare genetic disorder primarily involving digit abnormalities, scoliosis and club feet.
Silver-Russell dwarfism, also called Silver-Russell syndrome (SRS) or Russell-Silver syndrome (RSS) is a growth disorder occurring in approximately 1/75000 births. In the United States it is usually referred to as Russel-Silver Syndrome, and Silver-Russell Syndrome elsewhere. It is one of 200 types of dwarfism and one of five types of primordial dwarfism and is one of the few forms that is considered treatable. Its exact cause is unknown, but present research points toward a genetic component, possibly following maternal genes. There is no statistical significance of the syndrome occurring in males or
Chédiak-Higashi like syndrome, (also known as Griscelli syndrome, Silvery hair syndrome, or Albinism partial immunodeficiency) is a similar rare childhood autosomal recessive disorder that causes hypopigmentation of the skin and the hair, and can cause a fatal hemophagocytic syndrome, for which the only cure is bone-marrow transplantation. Chédiak-Higashi syndrome is a rare childhood autosomal recessive disorder that affects multiple systems of the body, which arises from a mutation in the lysosomal trafficking regulator gene, LYST. It is a disease with impaired bacteriolysis due to failure of phagolysosome formation. As a result of disordered intracellular trafficking there is impaired lysosome degranulation with phagosomes, so phagocytosed bacteria are not destroyed by the lysosome's enzymes. In addition secretion of lytic secretory granules by cytotoxic T cells is also affected. The disease is characterised by large lysosome vesicles in phagocytes, which thus have poor bactericidal function, leading susceptibility to infections, abnormalities in nuclear structure of leukocytes, anaemia, and hepatomegaly.
Simian B virus infection: A type of herpesvirus which occurs in monkeys but can be transmitted to humans through bites or through contact with infected monkey tissue as in a laboratory situation. The virus infects the brain (encephalitis) and the surrounding membrane (meningitis).
Simosa craniofacial syndrome: A rare disorder characterized by a range of facial anomalies including a high forehead, long face, flat face and a small mouth.
Simpson-Golabi-Behmel syndrome (SGBS) is a rare X-linked recessive inherited condition. It causes general overgrowth in height and weight. Individuals with SGBS also have characteristic facial features in childhood which tend to become less obvious in adulthood. SGBS is also known as Simpson dysmorphia syndrome (SDYS), bulldog syndrome, Golabi-Rosen syndrome, and dysplasia gigantism syndrome X-linked (DGSX). SGBS is a rare X-linked recessive inherited condition. Individuals with this condition have increased height and weight for their age; a broad, stocky appearance; a large protruding jaw; a short, broad nose; incomplete closure of the roof of the mouth (cleft palate); and broad, short hands and fingers. Individuals with SGBS are usually taller than average. The characteristic features usually become less apparent in adulthood. There are at least two genes for SGBS. Both genes are located on the X chromosome.
Scleroderma sine scleroderma: A very rare condition where the organ involvement normally associated with scleroderma is present but there are none of the characteristic skin symptoms. The degree of organ involvement is variable.
Singh-Chhaparwal-Dhanda syndrome: A very rare syndrome characterized mainly by short stature, mental retardation, eye defects and a missing kneecap.
Single upper central incisor: A very rare syndrome characterized by various defects in the middle of the face.
Single ventricle is one of the most complex and rare types of heart defects present at birth (congenital heart defect). It occurs when the fetal heart does not develop normally early in the first trimester of pregnancy. Prenatal heart circulation is different than adults and the heart continues to evolve after birth.The fetal heart begins its development as a long tube. During the first trimester, the lower part of this tube normally divides into two pumping chambers: the left ventricle and the right ventricle. However, there are rare cases in which this normal separation does not occur, and the baby is born with one functional ventricle instead of two. As a result of this defect, oxygen-rich blood and oxygen-poor blood mix together in the single ventricle instead of remaining separate. Some oxygen-rich blood needlessly travels back to the lungs, and some oxygen-poor blood uselessly travels to the rest of the oxygen-demanding body. Unless corrected surgically, single ventricle usually results in heart failure and death. However, surgical correction is available. Most patients will undergo at least two surgeries to correct single ventricle: the bi-directional Glenn (or the hemi-Fontan) and the Fontan. Together, these operations redirect oxygen–poor blood from the body straight to the lungs, bypassing the heart. In turn, the single ventricle is responsible for pumping freshly oxygenated blood to the body. Although these procedures may correct the defect, no procedure may cure it.
Singleton-Merten Syndrome: A very rare disorder involving calcium abnormalities which affect the teeth, bones and blood vessels.
Sino-auricular heart block: A rare heart condition caused by abnormalities in the heart's electrical system rather than arterial disease.
Sinonasal undifferentiated carcinoma: A rare but aggressive tumor that occurs in the nasal or sinus cavities.
Sinus Cancer (also known as cancer of the paranasal sinus and nasal cavity) occurs when cancer cells are found in the tissues of the paranasal sinuses or nasal cavity. The paranasal sinuses are small hollow spaces around the nose. The sinuses are lined with cells that make mucus, which keeps the nose from drying out; the sinuses are also a space through which the voice can echo to make sounds when a person talks or sings. The nasal cavity is the passageway just behind the nose through which air passes on the way to the throat during breathing. The area inside the nose is called the nasal vestibule.
Sinus histiocytosis: Another name for Rosai-Dorfman disease (or close medical condition association). Rosai-Dorfman disease: A rare condition characterized by excessive production and accumulation of a particular white blood cell (histiocyte). Accumulation primarily occurs in the lymph nodes, especially in the neck, but may also occur in the skin, central nervous system, digestive tract and kidneys.
Sinus node disease and myopia: A very rare disorder characterized by nearsightedness.
Sirenomelia is a lethal birth defect of the lower body characterized by apparent fusion of the legs into a single lower limb. Other birth defects are always associated with sirenomelia, most commonly abnormalities of the kidneys, large intestines, and genitalia. This pattern of birth defects is associated with abnormal umbilical cord blood vessels. The normal fetus develops two umbilical arteries, which pump blood from the fetus to the placenta, and one umbilical vein, which returns blood from the placenta to the fetus. The umbilical arteries branch off the iliac arteries in the pelvis. The iliac arteries supply the legs and pelvic organs such as the genitalia. Most babies with sirenomelia have only one umbilical artery and one vein. Rarely a baby with sirenomelia can have the typical two arteries and one vein with occlusion (blockage) of one artery. In sirenomelia, the one functional artery is larger than normal and branches from the aorta high in the abdomen. Below this umbilical artery, the aorta becomes abnormally narrow. This type of single umbilical artery is known as a vitelline artery because it is thought to arise from the primitive vitelline arteries early in the life of the embryo. The vitelline arteries normally fuse a few weeks after conception to form the arteries that supply the gastrointestinal system and genitourinary system (superior mesenteric, inferior mesenteric, and celiac arteries). If the normal umbilical arteries do not form correctly as branches from the iliac arteries, then a vitelline artery might persist. The vitelline umbilical artery steals blood and nutrition from the lower body and diverts it to the placenta. This results in a small aorta and variable absence of the arteries that supply the kidneys, large intestine, and genitalia (renal, inferior mesenteric, and celiac arteries). Because of the loss of nutrition and blood flow, the lower limbs fail to form as separate limbs, the kidneys do not form or are malformed, the large intestine ends blindly in the abdominal cavity, the anus is imperforate, and the internal and external genitalia are absent or malformed. The typical malformation of the lower limbs seen in babies with sirenomelia consists of apparent fusion of the legs. There is a spectrum of severity with severe cases having one lower limb that tapers to a point with the absence of foot structures. In these severe cases there are only two bones present in the entire limb (a femur and presumably a tibia). On the mild end of the spectrum are babies with fusion of the skin of the lower limbs only. In these infants the feet may be fully formed with fusion at the ankles. All bones are fully formed and separate. Normally there are three bones in each leg—the femur in the upper leg (thigh) and the tibia and fibula in the lower leg (calf). Other birth abnormalities of the upper body involving the heart, lungs, spine, brain, and arms can also be seen in this syndrome, however, not in every affected individual. It is unknown at this time why a single umbilical artery could cause these changes. Single umbilical artery occurs in about 1% of all live-born infants. In most of these infants the one umbilical artery is normally formed and not of vitelline origin. In these cases, the risk of other birth defects is low (about 8%). All infants born with a vitelline umbilical artery will have other malformations, the most common being sirenomelia.
Sitosterolemia (also known as phytosterolemia) is a rare autosomal recessively inherited lipid metabolic disorder. It is characterized by hyperabsorption and decreased biliary excretion of dietary sterols leading to hypercholesterolemia, tendon and tuberous xanthomas, premature development of atherosclerosis, and abnormal hematologic and liver function test results.
Situs inversus totalis with cystic dysplasia of kidneys and pancreas: A rare syndrome where the position of the internal organs of the chest and abdomen is transposed. In addition there are kidney and pancreatic abnormalities.
Situs inversus (also called situs transversus) is a congenital condition in which the major visceral organs are reversed or mirrored from their normal positions. The normal arrangement is known as situs solitus. In other rare cases, in a condition known as situs ambiguus or heterotaxy, situs cannot be determined. The term situs inversus is a short form of the Latin phrase "situs inversus viscerum," meaning "inverted position of the internal organs." Dextrocardia (the heart being located on the right side of the thorax) was first recognised by Marco Severino in 1643. However, situs inversus was first described more than a century later by Matthew Baillie.