Diseases

Ankylosing spondylitis

Ankylosing spondylitis (AS) is an inflammatory disease that can cause some of the vertebrae in your spine to fuse together. This fusing makes the spine less flexible and can result in a hunched-forward posture. This is characterized by back pain and stiffness that typically appear in adolescence or early adulthood. Over time, back movement gradually becomes limited as the bones of the spine (vertebrae) fuse together. This progressive bony fusion is called ankylosis.If ribs are affected, it may be difficult to breathe deeply.

Ankylosing spondylitis affects men more often than women. Signs and symptoms of ankylosing spondylitis typically begin in early adulthood. Inflammation also can occur in other parts of your body — most commonly, your eyes.

The earliest symptoms of ankylosing spondylitis result from inflammation of the joints between the pelvic bones (the ilia) and the base of the spine (the sacrum). These joints are called sacroiliac joints, and inflammation of these joints is known as sacroiliitis. The inflammation gradually spreads to the joints between the vertebrae, causing a condition called spondylitis. Ankylosing spondylitis can involve other joints as well, including the shoulders, hips, and, less often, the knees. As the disease progresses, it can affect the joints between the spine and ribs, restricting movement of the chest and making it difficult to breathe deeply. People with advanced disease are also more prone to fractures of the vertebrae.

Ankylosing spondylitis affects the eyes in up to 40 percent of cases, leading to episodes of eye inflammation called acute iritis. Acute iritis causes eye pain and increased sensitivity to light (photophobia). Rarely, ankylosing spondylitis can also cause serious complications involving the heart, lungs, and nervous system

There is no cure for ankylosing spondylitis, but treatments can decrease your pain and lessen your symptoms.

Ankylosis of teeth

A rare genetic disorder where the teeth fuse to the bone which can prevent them from erupting.

Annular constricting bands

Bands of amniotic tissue which can constrict parts of the body (especially the limbs) and result in deformity, swelling or even amputation of a body part. The severity and part of the body involved varies from case to case.

Annular pancreas

Annular pancreas is a rare condition in which the second part of the duodenum is surrounded by a ring of pancreatic tissue continuous with the head of the pancreas. This portion of the pancreas can constrict the duodenum and block or impair the flow of food to the rest of the intestines. It occurs in 1 out of 12,000 to 15,000 newborns. The ambiguity arises from the fact that not all cases are symptomatic.

Annuloaortic ectasia

Familial thoracic aortic aneurysm and dissection (familial TAAD) involves problems with the aorta, which is the large blood vessel that distributes blood from the heart to the rest of the body. Familial TAAD affects the upper part of the aorta, near the heart. This part of the aorta is called the thoracic aorta because it is located in the chest (thorax). Other vessels that carry blood from the heart to the rest of the body (arteries) can also be affected.

In familial TAAD, the aorta can become weakened and stretched (aortic dilatation), which can lead to a bulge in the blood vessel wall (an aneurysm). Aortic dilatation may also lead to a sudden tearing of the layers in the aorta wall (aortic dissection), allowing blood to flow abnormally between the layers. These aortic abnormalities are potentially life-threatening because they can decrease blood flow to other parts of the body such as the brain or other vital organs, or cause the aorta to break open (rupture).

The occurrence and timing of these aortic abnormalities vary, even within the same affected family. They can begin in childhood or not occur until late in life. Aortic dilatation is generally the first feature of familial TAAD to develop, although in some affected individuals dissection occurs with little or no aortic dilatation.

Aortic aneurysms usually have no symptoms. However, depending on the size, growth rate, and location of these abnormalities, they can cause pain in the jaw, neck, chest, or back; swelling in the arms, neck, or head; difficult or painful swallowing; hoarseness; shortness of breath; wheezing; a chronic cough; or coughing up blood. Aortic dissections usually cause severe, sudden chest or back pain, and may also result in unusually pale skin (pallor), a very faint pulse, numbness or tingling (paresthesias) in one or more limbs, or paralysis.

Familial TAAD may not be associated with other signs and symptoms. However, some individuals in affected families show mild features of related conditions called Marfan syndrome or Loeys-Dietz syndrome. These features include tall stature, stretch marks on the skin, an unusually large range of joint movement (joint hypermobility), and either a sunken or protruding chest. Occasionally, people with familial TAAD develop aneurysms in the brain or in the section of the aorta located in the abdomen (abdominal aorta). Some people with familial TAAD have heart abnormalities that are present from birth (congenital). Affected individuals may also have a soft out-pouching in the lower abdomen (inguinal hernia), an abnormal curvature of the spine (scoliosis), or a purplish skin discoloration (livedo reticularis) caused by abnormalities in the tiny blood vessels of the skin (dermal capillaries). However, these conditions are also common in the general population. Depending on the genetic cause of familial TAAD in particular families, they may have an increased risk of developing blockages in smaller arteries, which can lead to heart attack and stroke.

Anodontia

Anodontia is a dental condition characterized by complete absence of teeth. The primary (baby) or permanent (adult) teeth may be involved. Anodontia is extremely rare when present in a pure form (without associated abnormalities). In most cases, the phenomenon is associated with a group of conditions called the ectodermal dysplasias. In these cases, abnormalities are also noted in the hair, nails, and sweat glands.

Congenital absence of permanent teeth can present as hypodontia, usually missing 1 or 2 permanent teeth, or oligodontia that is the congenital absence of more than 6 teeth. Congenital absence of all wisdom teeth, or third molars, is relatively common. Anodontia is the congenital absence of teeth and can occur in some or all teeth (partial anodontia or hypodontia), involve two dentitions or only teeth of the permanent dentition (Dorland's 1998). Approximately 1% of the population suffers from oligodontia. Many denominations are attributed to this anomaly: partial anodontia, hypodontia, oligodontia, the congenital absence, anodontia, bilateral aplasia. Anodontia being the term used in controlled vocabulary Medical Subject Headings (MeSH) from MEDLINE which was developed by the United States National Library of Medicine. The congenital absence of at least one permanent tooth is the most common dental anomaly and may contribute to masticator dysfunction, speech impairment, aesthetic problems, and malocclusion (Shapiro and Farrington 1983). Absence of lateral incisors represents a major stereotype. Individuals with this condition are perceived as socially most aggressive compared with people without anodontia (Shaw 1981).

Anonychia congenita

Anonychia congenita is an extremely rare nail disorder characterized by the complete absence (anonychia) or abnormally developed fingernails and toenails. Affected individuals usually do not have hair, teeth, or bone abnormalities. Less than 20 individuals with anonychia congenita have been identified.

Anonychia ectrodactyly

A very rare syndrome characterized by the absence of nails and the absence of all or part of one or more fingers or toes (ectrodactyly).

Anonychia-onychodystrophy with hypoplasia or absence of distal phalanges

This syndrome, designated as Cooks syndrome, is characterized by nail anomalies ranging from onychodystrophy (dystrophic nails) to anonychia (absence of nails), associated with brachydactyly of the fifth finger, and digitalization of the thumbs (triphalangism). Eleven cases have been described in the literature so far. The distal phalanges of the hands and feet are either absent or hypoplastic. Among the 11 described cases, seven of the patients came from two generations of the same family with one instance of male-to-male transmission, and the other four patients came from three successive generations of another family with again an instance of male-to-male transmission. These observations suggest an autosomal dominant mode of inheritance. The syndrome should be distinguished from other nail disorders such as autosomal dominant anonychia-onychodystrophy: anonychia-onychodystrophy is not associated with bone changes and the nail hypoplasia is progressive from the fifth digit to the thumb, with anonychia often present in the second and third digits, whereas the nail hypoplasia in the thumb of patients with anonychia-onychodystrophy with hypoplasia or absence of the distal phalanges progresses to total nail absence in the fourth and fifth digits. In autosomal dominant brachydactyly with absence of the middle phalanges and hypoplastic nails, the changes in the middle phalanges are distinctive. In anonychia with ectrodactyly, digital anomalies are asymmetric, including absence of one or more digits. In '20-nail dystrophy', dystrophy of the nails progresses with age, whereas in patients with anonychia-onychodystrophy with hypoplasia or absence of the distal phalanges syndrome the nail findings are present from birth

Anophthalmia

Anophthalmia refers to comlete absense of the globe in the presence of ocular adnexa (eyelids, conjunctiva, and lacrimal apparatus). Anophthalmia can be unilateral or bilateral and is a hetrognous condition with various etiologies. It can be isolated or can occur with other anomalies as part of a well defined syndrome. About one-third of individuals with anophthalmia have associated malformations. Heritable causes of anophthalmia include chromosome abnormalities and syndromic or non syndromic single gene disorders. 

Mutations in the following genes are associated with Anophthalmia: SIX3, HESX1, BCOR, SHH, PAX6, RAX, SOX2 (SOX2 related eye disorders), POMT1 (Walker-Warburg Syndrome) and SIX6. 

Syndromic Anophthalmia: 

  • SOX2-related eye disorders
  • PAX6-related eye disorders  
  • Waardenburg anophthalmia syndrome
  • Delleman syndrome
  • Anophthalmia-plus syndrome

Anorchia

Anorchia (or anorchism) is an XY disorder of sex development in which individuals have both testes absent at birth. Within a few weeks of fertilization, the embryo develops rudimentary gonads (testes), which produce hormones responsible for the development of the reproductive system. If the testes fail to develop within eight weeks, the baby will develop female genitalia (see Swyer syndrome). If the testes begin to develop but are lost or cease to function between eight and 10 weeks, the baby will have ambiguous genitalia when it is born. However, if the testes are lost after 14 weeks, the baby will have partial male genitalia with the notable absence of gonads.

Tests include observable lack of testes, low testosterone levels (typical female levels), elevated follicle stimulating hormone and luteinizing hormone levels, XY karyotype, ultrasound or magnetic resonance imaging showing absent gonadal tissue, low bone density, low anti-Müllerian hormone levels, and surgical exploration for evidence of male gonadal tissue.

Anorectal atresia

Anorectal atresia is birth defect in which the rectum is malformed. It is a spectrum of different congenital anomalies in males and females, that varies from fairly minor lesions to complex anomalies. 

Anterior horn disease

The anterior horn of the spinal cord (or anterior cornu, or anterior column, or ventral horn) is the ventral (front) grey matter section of the spinal cord. The anterior horn contains motor neurons that affect the axial muscles while the posterior horn receives information regarding touch and sensation. The anterior horn is where the cell bodies of alpha motorneurons are located.

Anterior ischemic optic neuropathy

Anterior ischemic optic neuropathy (AION) is a medical condition involving loss of vision due to damage to the optic nerve from insufficient blood supply. AION is generally divided into two types: arteritic AION (or AAION) and non-arteritic AION (NAION or simply AION). This desription will focus primarily on non-arteritic AION.

The distinction between AAION and non-arteritic AION was made to highlight the different etiologies of anterior ischemic optic neuropathy. AAION is due to temporal arteritis (also called giant cell arteritis), an inflammatory disease of medium-sized blood vessels (Chapel-Hill-Conference) that occurs especially with advancing age. In contrast, NAION results from the coincidence of cardiovascular risk factors in a patient with "crowded" optic discs. Non-arteritic AION is more common than AAION and usually occurs in a slightly younger group than AAION. While only a few cases of NAION result in near total loss of vision, most cases of AAION involve nearly complete vision loss.

Anterior polar cataract 2

Anterior polar cataract 2 (CTAA2) is a rare, dominantly inherited type of cataract which is characterized by small opacities on the front surface of the eye lens. Vision is usually not affected and the cataract is not associated with any other abnormalities. Type 1 is caused by a genetic defect on chromosome 17p13.

Anterior segment mesenchymal dysgenesis

Anterior segment mesenchymal dysgenesis is an eye disorder caused by a genetic anomaly. The degree of vision impairment various with the severity of the condition. It is also called ASOD and ASMD.

Anterior spinal artery stroke

An interruption to the blood supply in the anterior spinal artery which affects sensation, motor control and bowel control. The symptoms may improve to varying degrees once the blood supply returns to normal. The severity of the disorder depends on the exact location of the defect and how long it persists for.

Anthrax

Anthrax is a life-threatening infectious disease that normally affects animals, especially ruminants (such as goats, cattle, sheep, and horses). Anthrax can be transmitted to humans by contact with infected animals or their products. In recent years, anthrax has received a great deal of attention as it has become clear that the infection can also be spread by a bioterrorist attack or by biological warfare. Anthrax does not spread from person to person.

Anti-NMDA Receptor Encephalitis

Anti-NMDA receptor (NMDAR) encephalitis is a newly identified autoimmune disorder that targets NMDARs, causing severe neurological symptoms including hallucinations, psychosis, and seizures, and may result in death. The disease was first characterized in 2007. It is the most common and best characterized antibody-related encephalitis.

N-Methyl-D-aspartate (NMDA) receptors play a key role in the plasticity of synapses (structures in nerve cells participating in signal transduction in the nervous system), which is believed to underlie memory and learning, as well as the development of the nervous system.

Movement disorder relapses after herpes simplex virus 1 (HSV1) encephalitis have been hypothesized to be secondary to postviral autoimmunity. Recently, a proportion of patients with HSV1 encephalitis (HSE) were shown to produce autoantibodies against NMDA receptors.

The condition is associated with tumours, mostly teratomas of the ovaries, and thus can be considered a paraneoplastic syndrome. However, there are a substantial number of cases with no detectable tumour, and in fact it appears that most patients do not have a tumour.

Antley-Bixler syndrome

A rare genetic disorder characterized by premature closing of skull bones, choanal atresia and craniofacial and limb abnormalities.

Anton’s syndrome

Anton–Babinski syndrome, also known as visual anosognosia, is a rare symptom of brain damage occurring in the occipital lobe. Those who suffer from it are "cortically blind", but affirm, often quite adamantly and in the face of clear evidence of their blindness, that they are capable of seeing. Failing to accept being blind, the sufferer dismisses evidence of their condition and employs confabulation to fill in the missing sensory input. It is named after Gabriel Anton and Joseph Babinski.

Aorta-pulmonary artery fistula

An abnormal opening or connection between the aorta and the main pulmonary artery. It can occur through a traumatic penetrating injury or may be a complication of surgery. Severe cases can lead to heart failure.

Aortic aneurysm- familial thoracic 3

A rare familial disorder where the aorta has a weak, bulging portion. The condition is asymptomatic but can result in death if it bursts. Type 3 is caused by a genetic defect on chromosome 3p22

Aortic aneurysm- familial thoracic 4

A rare familial disorder where the aorta has a weak, bulging portion. The condition is asymptomatic but can result in death if it bursts. Type 4 also involves another heart defect (patent ductus arteriosus) and is caused by a genetic defect on chromosome 16p13.13-p13.12.