Diseases

Huntington disease

Huntington disease (HD) is an inherited condition that causes progressive degeneration of neurons in the brain. Signs and symptoms usually develop between ages 35 to 44 years and may include uncontrolled movements, loss of intellectual abilities, and various emotional and psychiatric problems. People with HD usually live for about 15 to 20 years after the condition begins. It is caused by mutations in the HTT gene and is inherited in an autosomal dominant manner. Treatment is based on the symptoms present in each person and may include various medications.

There is also a less common, early-onset form of HD which begins in childhood or adolescence called juvenile Huntington disease.

Huntington’s disease

Huntington's disease is a disorder passed down through families in which nerve cells in certain parts of the brain waste away, or degenerate.

Hurler syndrome

Hurler syndrome (mucopolysaccharidosis type I, MPS I, Hurler's disease, gargoylism), is a genetic disorder that results in the buildup of glycosaminoglycans (formerly known as mucopolysaccharides) due to a deficiency of alpha-L iduronidase, an enzyme responsible for the degradation of mucopolysaccharides in lysosomes. Without this enzyme, a buildup of heparan sulfate and dermatan sulfate occurs in the body. Symptoms appear during childhood and early death can occur due to organ damage.

MPS I is divided into three subtypes based on severity of symptoms. All three types result from an absence of, or insufficient levels of, the enzyme α-L-iduronidase. MPS I H or Hurler syndrome is the most severe of the MPS I subtypes. The other two types are MPS I S or Scheie syndrome and MPS I H-S or Hurler-Scheie syndrome.

Hurler syndrome is often classified as a lysosomal storage disease, and is clinically related to Hunter Syndrome. Hunter syndrome is X-linked while Hurler syndrome is autosomal recessive.

It is named for Gertrud Hurler (1889–1965), a German pediatrician

Hurst Hallam Hockey syndrome

A group of malformation described in a stillborn infant. Defects include leptomeningeal angiomatosis (abnormal blood vessels in sheath surrounding brain and spinal cord), heart disease, cleft lip and palate and brain abnormalities

Hutchinson incisors

Abnormally shaped permanent front teeth (incisors). The defect is usually associated with congenital syphilis

Hutchinson-Gilford Progeria Syndrome

Progeria (pro-JEER-e-uh), also known as Hutchinson-Gilford progeria syndrome, is an extremely rare, progressive genetic disorder. It causes children to age rapidly, starting in their first two years of life.

Children with progeria generally appear healthy at birth. During the first year, symptoms such as slowed growth, loss of fat tissue and hair loss begin to appear.

Heart problems or strokes are the eventual cause of death in most children with progeria. The average life expectancy for a child with progeria is about 15 years. Some with the condition may die younger and others may live longer, even to about 20 years.

 

Hutteroth Spranger syndrome

A very rare syndrome characterized mainly by mental retardation, short stature and heart and skeletal anomalies

Hyalinosis systemic short stature

Ophanet, a consortium of European partners, currently defines a condition rare when if affects 1 person per 2,000. They list Hyalinosis systemic short stature as a "rare disease".

Hydatidosis

A parasitic infection caused by a tapeworm larva called echinococci. The type and severity of symptoms is determined by the location of the infestation - the most common site for the larval cysts is the liver. The most common symptoms are due to compression of nearby organs or blood vessels due to increasing size of the cyst. The larva may incubate for months or even years

Hyde Forster Mccarthy Berry syndrome

Hyde Forster Mccarthy Berry syndrome (medical condition): A very rare syndrome characterized mainly by mental retardation and an abnormal skull shape

Hydranencephaly

Hydranencephaly is a rare condition in which the brain's cerebral hemispheres are absent and replaced by sacs filled with cerebrospinal fluid. (

Hydroa vacciniforme

A rare skin disorder characterized the development of crusting skin eruptions following exposure to the sun

Hydrocephalus

Hydrocephalus (from Greek hydro-, meaning "water", and kephalos, meaning "head") is a medical condition in which there is an abnormal accumulation of cerebrospinal fluid (CSF) in the brain. This causes increased intracranial pressure inside the skull and may cause progressive enlargement of the head if it occurs in childhood, potentially causing convulsion, tunnel vision, and mental disability. It was once informally called "Water on the brain."

Two types of hydrocephalus are commonly described non-communicating hydrocephalus and communicating hydrocephalus, although there is evidence that communicating forms can lead to obstruction of CSF flow in many instances.

In non-communicating hydrocephalus, the CSF in the ventricles can not reach the subarachnoid space. This results from obstruction of interventricular foramina, cerebral aqueduct, or the outflow foramens of the fourth ventricle (median and lateral apertures). The most common obstruction is in the cerebral aqueduct. A block at any of these sites leads rapidly to dilatation of one or more ventricles. If the skull is still pliable, as it is in children younger than 2 years, the head may enlarge.

In communicating hydrocephalus, the obstruction of CSF flow is in the subarachnoid space from prior bleeding or meningitis. This causes thickening of the arachnoid leading to blockage of the return-flow channels. In some patients, the spaces filled by CSF are uniformly enlarged without an increase in intercranial pressure. This special form of communicating hydrocephalus is called normal pressure hydrocephalus (NPH), which results specifically from impaired CSF reabsorption at the arachnoid granulations. NPH's clinical manifestations are gait abnormality, dementia, and involuntary urination. NPH usually occurs in elderly patients.

Hydrocephalus obesity hypogonadism

A very rare syndrome characterized mainly by obesity, buildup of fluid inside the skull (hydrocephalus) and impaired sex hormone production.

Hydrocephalus skeletal anomalies

A very rare syndrome characterized mainly by retarded growth, buildup of fluid (cerebrospinal fluid) inside the skull and various skeletal anomalies.

Hydrocephaly tall stature joint laxity

A very rare syndrome characterized mainly by a buildup of fluid inside the skull, abnormal brain development (corpus callosum) and a diaphragmatic hernia.

Hydrolethalus syndrome

A rare genetic disorder characterized by hydrocephalus, micrognathia and polydactyly.

Hydrops ectrodactyly syndactyly

More detailed information about the symptoms, causes, and treatments of Hydrops ectrodactyly syndactyly is available belo

Hydrops fetalis

Abnormal accumulation of fluid in the fetus which can be fatal. Excessive fluid leaves the blood and enters the tissues. It can have non-immune and immune (mother's immune system destroys fetal red blood cells).