Diseases

Holoprosencephaly

Holoprosencephaly is a disorder caused by the failure of the prosencephalon (the embryonic forebrain) to sufficiently divide into the double lobes of the cerebral hemispheres. The result is a single-lobed brain structure and severe skull and facial defects. In most cases of holoprosencephaly, the malformations are so severe that babies die before birth. In less severe cases, babies are born with normal or near-normal brain development and facial deformities that may affect the eyes, nose, and upper lip.

Holoprosencephaly caudal dysgenesis

A very rare syndrome where the tailbone and the portion above the tailbone (coccyx and sacrum) fail to develop. The brain also fails to divide into two lobes resulting in a single-lobed brain.

Holoprosencephaly deletion 2p

A very rare syndrome characterized mainly by the failure of the brain to separate into two lobes, facial deformities and various other anomalies.

Holt-Oram syndrome

A rare inherited disorder characterized by hand, arm and heart abnormalities. Bone abnormalities usually affect the left arm more than the right and occasionally only one arm and/or hand is affected.

Holzgreve Wagner Rehder syndrome

A rare genetic disorder characterized by extra fingers, cleft palate, heart abnormalities, growth retardation and various other anomalies.

Homocarnosinosis

A very rare metabolic disorder where a deficiency of homocarnosinase causes a harmful buildup of homcarnosine. Symptoms include mental retardation, retinal pigmentation and spastic diplegia.

Homocystinuria

Homocystinuria is an inherited disorder in which the body is unable to process certain building blocks of proteins (amino acids) properly. There are multiple forms of homocystinuria, which are distinguished by their signs and symptoms and genetic cause. The most common form-called cystathionine beta-synthase deficiency, is characterized by nearsightedness (myopia), dislocation of the lens at the front of the eye, an increased risk of abnormal blood clotting, and brittle bones that are prone to fracture (osteoporosis) or other skeletal abnormalities. Some affected individuals also have developmental delay and learning problems.

Less common forms of homocystinuria can cause intellectual disability, failure to grow and gain weight at the expected rate (failure to thrive), seizures, problems with movement, and a blood disorder called megaloblastic anemia. Mutations in the CBS, MTHFR, MTR, and MTRR genes cause homocystinuria, and it is inherited in an autosomal recessive manner. Treatment varies depending upon the cause of the disorder.

Homocystinuria due to defect in methylation (cbl g)

An inherited organic acid disorder where an enzyme deficiency (methionine synthase) impairs the body's ability to break down certain proteins consumed in the diet. This results in a buildup of methylmalonic acid and homocystine which results in harmful affects. It is a form of vitamin B12 deficiency.

Homocystinuria due to defect in methylation cbl e

An inherited organic acid disorder where an enzyme deficiency (methionine synthase reductase) impairs the body's ability to break down certain proteins consumed in the diet. This results in a buildup of methylmalonic acid and homocystine which results in harmful affects. It is a form of vitamin B12 deficiency.

Homologous wasting disease

In most transplants, the patient's body may attempt to reject the transplanted organ (transplant rejection). However, in GVHD, the reverse happens; immune cells from the transplant attack the patient's cells.

Homozygous Familial Hypercholesterolemia

Homozygous familial hypercholesterolemia, also known as Autosomal recessive hypercholesterolemia (ADH), is characterized by high levels of low-density lipoprotein (LDL) cholesterol, and associated with premature cardiovascular disease and myocardial infarction. Approximately 1:500 individuals worldwide are affected by ADH. Most ADH is caused by genetic variants leading to decreased intracellular uptake of cholesterol. The majority of these cases have familial hypercholesterolemia (FH), which is due to mutations in the LDLR gene, which encodes for the LDL receptor. Approximately 15% of ADH cases have familial defective apolipoprotein B-100 (FDB) due to mutations in the LDL receptor-binding domain of the APOB gene, which encodes for apolipoprotein B-100.

Homozygous hypobetalipoproteinemia

Inherited low blood betalipoprotein level. The type and severity of symptoms is determined by whether or not there are some betalipoproteins in the body.

Hooft disease

A rare disorder characterized by mental and physical retardation, red rash and low blood lipid level

Hoon Hall syndrome

A very rare syndrome characterized mainly by dislocated joints and various other skeletal abnormalities.

Horn Kolb syndrome

congenital malformation involving symmetrically absent hands and feet. Little lumps on the ends of the limbs may be all that remains of the fingers and toes.

Horner’s syndrome

Horner syndrome is a rare condition that affects the nerves to the eye and face.

Hornova Dlurosova syndrome

A rare disorder characterized by mental retardation and amyloid (abnormal protein) deposits in the eyelids and gums.

Horseshoe kidney

The horseshoe kidney is the most common type of renal fusion anomaly. It consists of two distinct functioning kidneys on each side of the midline, connected at the lower poles by an isthmus of functioning renal parenchyma or fibrous tissue that crosses the midline of the body.

Horton’s disease

A systemic autoimmune vasculitis occurring primarily in people over the age of 50. Pathologic features include a necrotizing panarteritis including granulomas and giant cells. There is a predilection for involvement of central nervous system blood vessels and the most frequent neurologic complication is an OPTIC NEUROPATHY, ISCHEMIC. Large blood vessels may become involved, including the aorta. Clinical manifestations may include myalgias, weight loss, headache, visual loss, necrosis of the skin or tongue, and chest discomfort. Superficial scalp arteries may become tender and enlarged. A related condition, juvenile temporal arteritis, tends to occur in the first or second decade of life.

Howard Young syndrome

A very rare syndrome characterized mainly by a small head, facial cleft and an extra big toe. More detailed information about the symptoms, causes, and treatments of Howard-Young syndrome is available

Hoyeraal-Hreidarsson syndrome

Hoyeraal-Hreidarsson syndrome (HHS) is a very rare multisystem X-linked recessive disorder characterized by excessively short telomeres and is considered a severe form of dyskeratosis congenita. Being an X-linked disorder, HHS primarily affects males. Patients with HHS typically present in early childhood with cerebellar hypoplasia, immunodeficiency, progressive bone marrow failure, and intrauterine growth retardation. The primary cause of death in HHS is bone marrow failure, but mortality from cancer and pulmonary fibrosis is also significant.

Human granulocytic ehrlichiosis

A rare infectious condition caused by infection with a type of bacteria called Ehrlichia (Anaplasma phagocytophilia) which attack granulocytes (a type of white blood cell). The infection is transmitted by the deer and American dog tick