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.
Situs inversus, X-linked: A X-linked (occurs only in males but females can be carriers) disorder where the position of the internal organs of the chest and abdomen is transposed. For example, the heart is on the right side of the chest instead of the left. Generally this condition poses no problems but may become relevant during surgery or medical examinations as organs will be on the wrong side of the body.
Sixth nerve palsy, or abducens nerve palsy, is a disorder associated with dysfunction of cranial nerve VI (the abducens nerve) which is responsible for contracting the lateral rectus muscle to abduct (i.e. turn out) the eye. The inability of an eye to turn outward results in a convergent strabismus or esotropia of which the primary symptom is double vision or diplopia in which the two images appear side-by-side. The condition is commonly unilateral, but can also occur bilaterally.
Sjogren-Larsson syndrome is an inborn error of lipid metabolism, characterized by congenital ichthyosis (dry, scaly skin), intellectual disability, and spasticity (stiffness and involuntary muscle spasms). These symptoms are apparent by early childhood and usually do not worsen with age. SLS is an autosomal recessive form of ichthyosis apparent at birth. Sjögren–Larsson syndrome is a rare autosomal, recessive, neurocutaneous disease. This disease can be identified by a triad of medical disorders. The first is ichthyosis, which is a buildup of skin to form a scale-like covering that causes dry skin and other problems. The second identifier is spastic paraplegia which is characterized by leg spasms. The final identifier is intellectual delay. The gene of SLS is found on chromosome 17. In order for a child to receive SLS both parents must be carriers of the SLS gene. If they are carriers their child has a ¼ chance of getting the disease. In 1957 Sjogren and Larsson proposed that the Swedes with the disease all descended from a common ancestor 600 years ago. Today only 30-40 persons in Sweden have this disease.
Affected infants tend to be born prematurely. At birth the skin is red (erythema), but later in infancy the skin becomes dry, rough, and scaly with a brownish or yellowish tone. Mild to severe itchiness (pruritus) is also common. These skin abnormalities are generally dispersed over the whole body, most severely affecting the nape of the neck, the torso, and the extremities. The skin of the face is usually not affected.
People with this condition may also have neurological signs and symptoms. Most affected individuals have leukoencephalopathy, which is a change in a type of brain tissue called white matter. White matter consists of nerve fibers covered by a substance (myelin) that insulates and protects the nerves. The leukoencephalopathy is thought to contribute to many of the neurological signs and symptoms in people with Sjögren-Larsson syndrome. Most affected individuals have intellectual disability that varies from mild to profound and is usually apparent by early childhood. People with Sjögren-Larsson syndrome have speech difficulties (dysarthria) and delayed speech. Usually they are able to produce only short sentences with poorly formed words. Rarely, people with this condition have normal intelligence. In addition, approximately 40 percent of people with Sjögren-Larsson syndrome have seizures.
Children with this condition often experience delayed development of motor skills (such as crawling and walking) due to abnormal muscle stiffness (spasticity) that is typically in their legs and, less commonly, also in their arms. About one-half of people with Sjögren-Larsson syndrome require wheelchair assistance and many others need some form of support to walk.
Affected individuals have tiny crystals in the light-sensitive tissue at the back of the eye (retina) that can be seen during an eye exam. Based on their appearance, these retinal crystals are often called glistening white dots. These white dots are usually apparent by early childhood, and it is unclear if they affect normal vision. People with Sjögren-Larsson syndrome may also have nearsightedness (myopia) or an increased sensitivity to light (photophobia).
Sjogren-Larsson-like syndrome: A very rare syndrome characterized by a thickened scaly skin similar to that observed in sufferers of Sjogren-Larsson syndrome.