Diseases

Hydroxykynureninuria

A rare genetic disorder where a deficiency of the enzyme kynureninase (a vitamin B6) causes physical and mental problems. The deficiency can also occur in an acquired form which tends to be less severe

Hygroma cervical

An abnormal sac-like structure filled with lymph fluid that occurs in the neck area. It results from abnormal lymphatic structure development. The abnormality is present at birth and may vary in size from barely noticeable to large enough to affect breathing. Surgical removal can result in recurrence of all of the tissue is not removed. In some cases, the hygroma is too intertwined with other structures and surgery is not possible

Hymenolepiasis

A rare parasitic disease caused by a tapeworm called Hymenolepis nana or Hymenlepis dimunita. Infestation occurs through fecal contamination or by accidentally consuming insects that have eaten the parasitic eggs.

Hyper IgM syndrome

A rare inherited immunodeficiency disorder which causes frequent infections involving the ears, eyes, sinuses, lungs, skin, respiratory tract and other areas of the body. This condition is inherited in an X-linked recessive pattern.

X-linked hyper IgM syndrome is a condition that affects the immune system and occurs almost exclusively in males. People with this disorder have abnormal levels of proteins called antibodies or immunoglobulins. Antibodies help protect the body against infection by attaching to specific foreign particles and germs, marking them for destruction. There are several classes of antibodies, and each one has a different function in the immune system. Although the name of this condition implies that affected individuals always have high levels of immunoglobulin M (IgM), some people have normal levels of this antibody. People with X-linked hyper IgM syndrome have low levels of three other classes of antibodies: immunoglobulin G (IgG), immunoglobulin A (IgA), and immunoglobulin E (IgE). The lack of certain antibody classes makes it difficult for people with this disorder to fight off infections.

Hyper-IgD syndrome

Hyper IgD syndrome (HIDS) is an inflammatory genetic where high levels of the immunoglobulin D cause disorder characterized by periodic episodes of fever associated with additional symptoms including joint pain, skin rash and abdominal pain. Most episodes last several days and occur periodically throughout life. The frequency of episodes and their severity vary greatly from case to case. It is originally described in 1984 by the Prof. Jos van der Meer at Leiden University Medical Centre.

Hyper-IgE Syndrome

Hyper-IgE syndrome (HIES, also called Job-Buckley syndrome, Job's syndrome and Buckley syndrome), is a heterogeneous group of disorders characterized by recurrent staphylococcal infections, unusual eczema-like skin rashes, severe lung infections that result in pneumatoceles (balloon-like lesions that may be filled with air or pus or scar tissue) and very high concentrations of the serum antibody IgE.

Hyper-reninism

An autonomous, excessive renin-producing tumor results secondary hyperaldosteronism with the subsequent hypertension

Hyperacusis

Hyperacusis is a health condition characterized by an over-sensitivity to certain frequency ranges of sound (a collapsed tolerance to normal environmental sound). A person with severe hyperacusis has difficulty tolerating everyday sounds, some of which may seem unpleasantly loud to that person but not to others.

Hyperadrenalism

Hyperadrenalism (medical condition): Excessive levels of adrenal hormones in the body. Symptoms depend on which hormone is involved and the degree of involvement. Adrenal hormones are aldosterone, corticosteroids, androgenic steroids, epinephrine and norepinephrine.

Hyperaldosteronism

A condition characterised by the excessive production and release into the circulation of aldosterone

Hyperaldosteronism familial type 2

Type 2 familial hyperaldosteronism, inherited as an autosomal dominant trait, causes hypertension secondary to primary aldosteronism that is not suppressed with dexamethasone. Patients present with an adrenal adenoma that secretes aldosterone. The observation of several families affected suggests that the molecular mechanism may be different than in type I familial hyperaldosteronism, but remains to be identified. Diagnostic suspicion should lead to the screening of patients by determining the aldosterone/renin ratio.

Hyperaldosteronism- familial type 1

Type I familial aldosteronism also called dexamethasone suppressible aldosteronism is a rare disorder inherited as an autosomal dominant trait. It is due to the ectopic expression of the aldosterone synthase in the fascicular zone of the adrenal gland. It is marked with early severe hypertension (often occurring before the age of 20), biological signs of primary aldosteronism of variable intensity, and an abnormal elevated level of 18-oxo- and 18-hydroxycortisol. The molecular defect is a recombination on the long arm of chromosome 8 leading a duplication-fusion between the 5' end of the gene coding for the 11 beta-hydroxylase (CYP11B1) and the 3' end of the gene coding for the aldosterone synthase (CYP11B2), two very similar (93%) and very closely located genes. All the modifications are located before the exon 5 of CYP11B2 which encodes amino acids allowing the aldosterone synthase function. The hybrid gene has the promoting part of CYP11B1, ACTH-sensitive, and the coding part of CYP11B2. This leads an excessive mineralocorticoids synthesis in the adrenal glands, governed by the hypothalamohypophyseal axis. Diagnosis and familial screening consist in providing evidence of the hybrid gene by Southern blot and/or PCR. Urinary tests show an important elevation of 18-oxo- and 18-hydroxycortisol. Once the diagnosis is ascertained, a specific treatment to slow the production of aldosterone is given; it combines small doses of dexamethasone and an anti-aldosterone

Hyperammonemia due to NAGS deficiency

Hyperammonemia due to N-Acetylglutamate synthase (NAGS) deficiency is a metabolic disturbance characterised by an excess amount of ammonia in the blood. Children with this severe urea cycle disorders typically show symptoms directly after the first 24 hours of life. Symptoms may include vomiting, lethargy, seizures, respiratory distress and coma. The basic tests to make the diagnosis are the measurement of blood ammonia, plasma amino acids and urine organic acids concentrations. Severe consequences can be avoided through direct medication in combination with a strict diet.

Hyperandrogenism

Excessive levels of androgen (male sex hormones) that can occur in males and females

Hyperbilirubinemia type 1

: Better known as Gilbert's disease, a common but harmless genetic condition in which a liver enzyme essential to the disposal of bilirubin (the chemical that results from the normal breakdown of hemoglobin from red blood cells) is abnormal. (The errant enzyme is called UDP- glucuronosyltransferase).

Hyperbilirubinemia type 2

Hyperbilirubinemia, also called neonatal jaundice, is the result of hemolytic processes in the neonate. It’s marked by elevated serum bilirubin levels and mild jaundice and can be physiologic (with jaundice the only symptom) or pathologic (resulting from an underlying disease). Physiologic jaundice tends to be more common and more severe in certain ethnic groups (Chinese, Japanese, Koreans, Native Americans), whose mean peak of unconjugated bilirubin is approximately twice that of the rest of the population. Physiologic jaundice is self-limiting; the prognosis for pathologic jaundice varies, depending on the cause.

Hypercalciuria- childhood idiopathic

A rare disorder occurring in children for no detectable reason where excess calcium is excreted through the urine resulting in the development of stones in the urinary tract.

Hypercementosis

A tooth disorder where excess cementum (bony covering of tooth root) is deposited on the roots of teeth. One or more teeth may be affected. Causes of excess cementum deposit include localized inflammation and certain metabolic disorders.

Hypercholesterolemia- autosomal dominant- type B

Autosomal dominant type IIa hypercholesterolaemia (ADH) is characterised by an elevation of total plasma cholesterol associated with increased LDL particles.Numerous different molecular defects have been identified in the LDL receptor (LDLR) and few specific mutations in the apolipoprotein B (APOB) gene resulting in familial hypercholesterolaemia and familial defective apoB-100 respectively.

Hyperchylomicronemia

* Triglycerides (TG) are fat (lipid) molecules that are made in the body from other sources such as carbohydrates, or are derived from food. Once TGs are absorbed through the intestines or made in the liver, they are carried via lipoproteins (carrier molecules) to tissues for use as fuel, and to fat cells (adipose tissue) for storage and later use, when energy is needed between meals. * High levels of TGs in the blood create a condition referred to as hypertriglyceridemia. Elevated levels of TGs can slow the flow of blood, and is now recognized as independent risk factor for heart disease -- the number one killer of people in the United States. * There are various types and subtypes of hypertriglyceridemia (I-V) based on the cause, lipid type, and clinical presentation of associated disorders. For example, type IV is associated with high VLDL, a major lipoprotein carrier that transports triglycerides across cell membranes and throughout the body.

Hypereosinophilic syndrome

Hypereosinophilic syndrome is a group of rare blood disorders characterized by increased levels of eosinophils (a type of white blood cell that plays a role in the human immune system) persisting for more than six months. The signs and symptoms are due to involvement of several internal organs and there is usually no evidence of parasites, allergy, or other known causes of an elevated eosinophil count. This condition largely occurs in males, typically at middle age. It usually presents with fever, weight loss, fatigue, and rash. An enlarged liver and spleen and liver is often present. The lungs, kidneys, heart, and nervous system can also be affected.

Hyperexplexia hereditary

Hyperexplexia is a rare autosomal dominant, hereditary, neurological disorder that may affect infants as newborns (neonatal) or prior to birth (in utero). It may also affect children and adults. Individuals with this disorder have an excessive startle reaction to sudden unexpected noise, movement, or touch. Symptoms include extreme muscle tension (stiffness or hypertonia) that can cause the affected person to fall stiffly, like a log, without loss of consciousness. Exaggeration of reflexes (hyperreflexia), and an unstable way of walking (gait) may also occur.

Hyperglycerolemia

A genetic condition where an enzyme deficiency (glycerol kinase) results in an accumulation of glycerol in the body as well as it's excretion through the urine.

Hyperglycinemia- isolated nonketotic type 2

Non ketotic hyperglycinemia with is relatively frequent among inborn errors of newborns. It is transmitted as an autosomal recessive trait. It affects hepatic glycine cleavage, which is the main source of monocarbon radicals. Onset is generally neonatal with coma, severe hypotonia, myoclonic seizures, and microcephaly. The disease usually progresses to severe mental retardation and tetrapyramidal syndrome. The electroencephalogram yields a characteristic hypoactive and pseudoperiodic chart with burts suppression. Biological findings are massive levels of glycine in plasma, urine, and especially cephalospinal fluid, while serine is low. The diagnosis is confirmed by measuring enzymatic activity in the liver. A few cases with later onset have been described (patients present with aspecific encephalopathy), as well as transient neonatal cases, which first present with a favourable disease course, whose long term outcome is finally disappointing. Treatment is based on sodium benzoate and dextromethorphane, but its efficiency has not been demonstrated. Genes encoding N or P subunit may carry different mutations. Antenatal diagnosis using a chorion villus sample may be performed by studying glycine cleavage (not reliable method) or by gene analysis if the mutation is known

Hyperhomocysteinemia

Hyperhomocysteinemia is a medical condition characterized by an abnormally large level of homocysteine in the blood. As a consequence of the biochemical reactions in which homocysteine is involved, deficiencies of the vitamins folic acid, pyridoxine (B6), or B12 can lead to high homocysteine levels. Supplementation with pyridoxine, folic acid, B12 or trimethylglycine (betaine) reduces the concentration of homocysteine in the bloodstream.

Hyperimidodipeptiduria

A very rare genetic disorder characterized by an excessive level of imidodipeptides in the urine due to a deficiency of the enzyme prolidase