Diseases

Alzheimer disease type 2

A degenerative brain disease characterized primarily by progressive dementia. Type 2 has a late onset - starts after the age of 65. In general, Alzheimer disease (AD) is a degenerative disease of the brain that causes gradual loss of memory, judgment and the ability to function socially. It is believed to be caused by a combination of genetic mutations and environmental and lifestyle factors. The condition occurs when there is excessive production of a toxic protein (amyloid beta peptide) in the brain which collects into clumps (amyloid plaques) in the brain. These plaques cause damage to nerve cells in the brain.

Alzheimer disease type 4

A degenerative brain disease characterized primarily by progressive dementia. Type 4 has an early onset (starts before the age of 65). It is caused by mutations in the PSEN2 gene which results in the production of a toxic protein (amyloid beta peptide) in the brain which collects into clumps (amyloid plaques) in the brain. These plaques cause damage to nerve cells in the brain.

Alzheimer disease- familial

Familial Alzheimer disease (familial AD) is a degenerative disease of the brain that causes gradual loss of memory, judgment, and the ability to function socially. About 25% of all Alzheimer disease is familial (more than 2 people in a family have AD). When Alzheimer disease begins before 60 or 65 years of age (early-onset AD) about 60% of the cases are familial (also known as Early-onset familial AD). These cases appear to be inherited in an autosomal dominant manner.

There are three subtypes of early-onset familial AD which are each associated with changes (mutations) in unique genes:
(1) Alzheimer disease, type 1 is caused by mutations in the APP gene
(2) Alzheimer disease, type 3 is caused by mutations in the PSEN1 gene
(3) Alzheimer disease, type 4 is caused by mutations in the PSEN2 gene.

The condition known as late-onset familial AD includes only the subtype Alzheimer disease, type 2 and is associated with the APOE 4 allele on chromosome 19. This condition results in an increased risk of having AD.

Amastia

Amastia refers to a condition where breast tissue, nipple, and areola is absent, either congenitally or iatrogenically. Amastia in girls can be treated with augmentation mammoplasty.

Amastia differs from amazia (which involves only the absence of breast tissue; the nipple and areola remain present), although the two conditions are often (erroneously) thought to be identical. The terms "amastia" and "amazia" are thus often used interchangeably, even though the two conditions are medically different.

Amaurosis fugax

Amaurosis fugax involves loss of vision in one eye caused by a temporary lack of blood flow to the retina.

Amaurosis hypertrichosis

Amaurosis hypertrichosis is a rare syndrome characterised by severe retinal dystrophy marked by visual impairment and profound photophobia without night blindness, associated with trichomegaly, bushy eyebrows with synophyrys, and excessive facial and body hair .

Ambras syndrome

Ambras syndrome is a very rare type of hypertrichosis lanuginosa congenita, a congenital skin disease characterized by excessive hair growth on the entire body, with the exception of the palms, soles, and mucous membranes. Individuals with Ambras syndrome have excessive growth of vellus (soft, fine and short) hair, especially on the face, ears, and shoulders. Facial and dental abnormalities may also be present. Ambras syndrome has been mapped to the short (q) arm of chromosome 8. It appears to follow an autosomal dominantpattern of inheritance.

Amebiasis

Amebiasis is an intestinal illness that's typically transmitted when someone eats or drinks something that's contaminated with the parasite Entamoeba histolytica (E. histolytica)-the parasite is an amoeba, a single celled organism. 

Most infected people, about 90%, are asymptomatic, but this disease has the potential to make the sufferer dangerously ill if not treated. It is estimated that about 40,000 to 100,000 people worldwide die annually due to amoebiasis. Infections can sometimes last for years. Until symptoms appear, can take a few days to weeks to develop and manifest.

Amelogenesis imperfecta

Amelogenesis imperfecta (AI) (amelogenesis - enamel formation; imperfecta - imperfect)is a group of rare, inherited disorders characterized by abnormal enamel formation. This term is restricted to those disorders of enamel development not associated with other defects of the body.

It (AI) is a disorder that affects the structure and appearance of the enamel of the teeth. This condition causes teeth to be unusually small, discolored, pitted or grooved, and prone to rapid wear and breakage. These dental problems, which vary among affected individuals, can affect both primary (baby) teeth and permanent teeth.

In this disorder, the layer of enamel is thin so that the teeth appear to be discolored, showing the color of the materials under the enamel. The teeth usually appear brown or some variant of that color.

In Clinical findings, it is usually classify AI into four main types and it is further 14 sub types are recognized, which are distinguished by their specific dental abnormalities and by their pattern of inheritance. The main types are based on enamel effects and the sub types are based on clinical appearance and mode of inheritance.

The main types are:

  • Hypoplastic (Type 1)
  • Hypomaturation (Type II)
  • Hypocalcified (Type III)
  • Hypomaturation/hypoplasia/taurodontism (Type IV)

Amelogenesis imperfecta may be inherited as an X-linked, autosomal dominant, or autosomal recessive genetic trait, depending on the type.

Amelogenesis Imperfecta hypomaturation type

Amelogenesis Imperfecta hypomaturation type (AIH) (medical condition) is subtype of Amelogenesis Imperfecta. Amelogenesis imperfecta is an inherited tooth development disorder characterized by tooth enamel defects. The hypomaturation type involves an abnormality during the maturation stage of enamel formation which causes the enamel to become porous and opaque.

In Amelogenesis Imperfecta hypomaturation type Varies from creamy opaque to marked yellow/brown, surface of teeth soft and rough, dental sensitivity and open bite common. In this type normal thickness with enamel that often chips and abrades easily. Also, the Enamel has contrast similar to or > than dentin, unerupted crowns have normal morphology. It is inherited autosomal dominant, recessive or X-linked.

Amelogenesis imperfecta local hypoplastic form

Amelogenesis imperfecta local hypoplastic form (medical condition): A rare inherited disorder involving abnormal formation of the tooth enamel. The type of abnormality may vary from pitted teeth to smooth teeth.

Amelogenesis imperfecta pigmented hypomaturation type

Amelogenesis imperfecta is an inherited tooth development disorder characterized by tooth enamel defects. The pigmented hypomaturation type is characterized by fragile tooth enamel which tends to be soft and rough and is usually a creamy to yellow/brown color. 

Amelogenesis imperfecta- hypoplastic/hypomaturation- X-linked 1

Amelogenesis imperfecta is an inherited tooth development disorder characterized by tooth enamel defects. The hypoplastic/hypomaturation X-linked 1 form is characterized by thin tooth enamel which is of normal strength. The surface of the enamel varies from smooth to pitted and the tooth color is variable. 

Aminoacidopathies

Any of a group of in born errors of metabolism which results in the build up in the body of one or more amino acids in the blood and/or urine. The range and severity of symptoms is hugely variable.

Aminoaciduria

Aminoaciduria is an abnormal amount of amino acids in the urine. Amino acids are the building blocks for proteins in the body. Small amounts of amino acids are also present in normal urine. Increased total urine amino acids may result from metabolic disorders, chronic liver disease or renal disorders. Aminoacidurias can be divided into primary and secondary aminoacidurias.

Aminoacylase 1 deficiency

A rare genetic disorder caused by an enzyme (aminoacylase-1) deficiency. It can cause neurological problems; the pattern and severity of signs and symptoms vary widely among affected individuals. Individuals with this condition typically have delayed development of mental and motor skills (psychomotor delay). They can have movement problems, reduced muscle tone (hypotonia), mild intellectual disability, and seizures. However, some people with aminoacylase 1 deficiency have no health problems related to the condition. A key feature common to all people with aminoacylase 1 deficiency is high levels of modified protein building blocks (amino acids), called N-acetylated amino acids, in the urine.

Amish lethal microcephaly

Amish lethal microcephaly is a disorder in which infants are born with a very small head and underdeveloped brain.

Infants with Amish lethal microcephaly have a sloping forehead and an extremely small head size. They may also have an unusually small lower jaw and chin (micrognathia) and an enlarged liver (hepatomegaly).

Affected infants may have seizures and difficulty maintaining their body temperature. Often they become very irritable starting in the second or third month of life. A compound called alpha-ketoglutaric acid can be detected in their urine (alpha-ketoglutaric aciduria), and during episodes of viral illness they tend to develop elevated levels of acid in the blood and tissues (metabolic acidosis). Infants with this disorder typically feed adequately but do not develop skills such as purposeful movement or the ability to track faces and sounds. Affected infants live only about six months.

Amniotic band syndrome

Amniotic band syndrome (ABS) refers to a condition in which bands extend from (and originating from) the inner lining of the amnion. The amnion is the sac that surrounds the baby in the womb. As the baby develops in the womb, its extremities may become entangled in the amniotic band resulting in constriction or even amputation. When this happens the baby is said to have amniotic band syndrome. Amniotic bands are thought to happen sporadically or in association with trauma to the abdomen. It can be a complication after an amniocentesis and/or it can indicate early rupture of the amniotic sac.

It is potentially associated with a variety of different birth defects. It is important to note that two cases of amniotic band syndrome are not exactly alike and associated symptoms are highly variable. The severity of this syndrome can range from a single, isolated finding to multiple, disfiguring complications. Most often legs and arms are affected but in some cases head and face as well as various internal organs have been affected.

Ampola syndrome

A rare genetic disease characterized primarily by mental retardation, facial anomalies, short stature, seizures and finger and toe abnormalities. More detailed information about the symptoms, causes, and treatments of Ampola syndrome is available below.

Amyloid Neuropathies

Disorders of peripheral nerves are the most common neurological complications of systemic amyloidosis; an illness where a protein called amyloid is deposited in tissues and organs. Amyloidosis can affect peripheral sensory, motor or autonomic nerves and deposition of amyloid lead to degeneration and dysfunction in these nerves.

Amyloidosis

Amyloidosis is a rare disease that results from the buildup of misfolded proteins known as amyloids. When proteins that are normally dissolvable in water fold to become amyloids, they become insoluble and deposit in organs or tissues, disrupting normal function. The type of protein that is misfolded and the organ or tissue in which the misfolded proteins are deposited determine the clinical manifestations of amyloidosis.

There are four main types of amyloidosis, each due to the deposition of a specific protein. The most common type is AL amyloidosis, caused by the deposition of light chain proteins produced by plasma cells in different disease states. The second most common is AA amyloidosis due to the accumulation of S amyloid A protein or SAA, which occurs in association with chronic infections - e.g. tuberculosis - or inflammatory illnesses such as rheumatoid arthritis. The third and the fourth type are due to the deposition of a genetically defective or normal form of a protein called transthyretin respectively. Other minor forms of amyloid are also known.

Amyopathic dermatomyositis

Amyopathic dermatomyositis (ADM) is a form of dermatomyositis characterized by the presence of typical skin findings without muscle weakness. Some of the skin changes that suggest dermatomyositis include a pink rash on the face, neck, forearms and upper chest; Gottron's papules and heliotrope eyelids. Pruritis and photosensitivity are common, as is scalp inflammation and thinning of the hair. While patients with amyopathic dermatomyositis should not have clinically evident muscle weakness, minor muscle abnormalities may be included. Fatigue is reported in at least 50% of patients. Some cases have been associated with internal malignancy and/or interstitial lung disease.