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All Communities

  • Hailey–Hailey Disease

    7 members

    Hailey–Hailey Disease is a rare genetic disorder that causes blisters to form on the skin.

  • Hajdu-Cheney Syndrome

    1 members

    Hajdu-Cheney Syndrome is a rare genetic disorder of the connective tissue.

  • Hallermann-Streiff Syndrome

    4 members

    Hallermann-Streiff Syndrome is a rare congenital disorder that affects growth, cranial development, hair growth and dental development.



  • Harboyan syndrome

    1 members

    Harboyan syndrome, also known as corneal dystrophy-perceptive deafness (CDPD), is an inherited, degenerative disorder characterized by congenital hereditary endothel...

  • Harding Ataxia

    2 members

    Harding Ataxia is rare disorder characterized by progressive damage to the nervous system.

  • Harlequin Syndrome

    16 members

    Harlequin syndrome is a rare disorder characterized by flushing and sweating on only one side of the face typically induced by heat or exercise.

  • Hartnup Syndrome

    2 members

    Hartnup Syndrome is a rare autosomal recessive metabolic disorder affecting the absorption of neutral amino acids.

  • Hashimoto's Encephalopathy

    16 members

    Hashimoto's Encephalopathy is a very rare condition associated with Hashimoto's Thyroiditis.

  • Heller's Syndrome

    5 members

    Heller's Syndrome is an extreme disorder that resembles autism. It is a disintegrative disorder that sets back the child's intelligence and social abilities.



    A normal chi...

  • Hemangiopericytoma

    7 members

    Hemangiopericytomas are rare vascular tumors coming from cells associated with capillary walls. These tumors can be found throughout the body,most commonly in the lower extremities, pelvic area, ...

  • Hemochromatosis

    8 members

    Hemochromatosis is a rare hereditary disease characterized by excessive absorption of dietary iron.

  • Hemoglobin Hasharon

    1 members

    Hemoglobin Hasharon is a rare blood disorder.

  • Hemophagocytic Lymphohistiocytosis

    6 members

    Hemophagocytic Lymphohistiocytosis is a disorder characterized by fever, splenomegaly, jaundice, and hemophagocytosis.



  • Hemophilia

    12 members

    Hemophilia is an inherited bleeding disorder which prevents the blood from clotting normally.

  • Heparin-Induced Thrombocytopenia

    1 members

    Heparin-induced thrombocytopenia is the development of thrombocytopenia due to the administration of heparin, an anticoagulant.

  • Hepatic Venoocclusive Disease

    1 members

    Hepatic Venoocclusive Disease is a disroder in which there is blockage of some of the small veins in the liver.

  • Hereditary Fructose Intolerance

    4 members

    Hereditary Fructose Intolerance is a rare genetic disorder caused by a deficiency of liver enzymes that metabolise fructose.

  • Hereditary Hyperferritinemia Cataract Syndrome


  • Hereditary Inclusion Body Myopathies

    5 members

    Hereditary Inclusion Body Myopathies are a group of rare genetic disorders causing progressive muscle wasting and weakness beginning in young adults.




  • Hereditary Multiple Exostoses

    16 members

    Multiple Hereditary Exostoses / Multiple Osteochondroma is a rare genetic bone condition in which multiple benign cartilage-capped bone tumors called exostoses / osteochondromas develop. They grow ...

  • Hereditary Pancreatitis

    10 members

    Hereditary Pancreatitis is a condition characterized by recurrent episodes of pancreatic attacks.

  • Hereditary Renal Adysplasia


    Hereditary Renal Adysplasia is a disorder in which one kidney is absent and the other is very small and malformed.

  • Hereditary Spherocytosis

    9 members

    Hereditary Spherocytosis is a genetic disorder characterized by the production of red blood cells that are more prone to hemolysis.

  • Hereditary Stomatocytosis


    Hereditary Stomatocytosis describes a number of inherited disorders that affect the outer coating of the red blood cells.



  • Hermansky-Pudlak Syndrome

    3 members

    Hermansky-Pudlak Syndrome is a rare form of albinism resulting in decreased pigmentation, platelet abnormality, legal blindness, and storage of an abnormal fat-protein compound.


  • Hidradenitis Suppurativa

    19 members

    Hidradenitis Suppurativa is a rare skin disease affecting areas bearing apocrine sweat glands and hair follicles.

  • HIDS

    5 members

    HIDS is a periodic fever syndrome characterized by attacks of fever, arthralgia, skin lesions including cyclical mouth ulcers, and diarrhea.

  • Hirschsprung Disease

    9 members

    Hirschsprung Disease is a rare disorder characterized by the enlargement of the colon due to bowel obstruction.

  • Histidinemia


    Histidinemia is a rare disorder caused by a deficiency of the enzyme histidase.

  • Hodgkin Lymphoma

    3 members

    Hodgkin Lymphoma is a rare type of cancer originating from a type of white blood cells called lymphocytes.

  • Holocarboxylase Synthetase Deficiency


    Holocarboxylase synthetase deficiency is a disorder in which the body is unable to use the vitamin biotin effectively.

  • Holoprosencephaly


    Holoprosencephaly is a rare disorder in which the brain does not develop into two hemispheres.

  • Holt-Oram Syndrome

    4 members

    Holt-Oram Syndrome is a rare disorder characterized by limb abnormalities, affecting the bones in the wrist and commonly the heart.

  • Homocystinuria

    5 members

    Homocystinuria is a rare genetic disorder affecting the metabolism of the amino acid methionine.

  • Horner's Syndrome

    5 members

    Horner syndrome is a rare disorder characterized by damage to the sympathetic nerves of the face and eye.

  • Human T-Lymphotropic Virus

    1 members

    Human T-Lymphotropic Virus is an RNA retrovirus that causes T-cell leukemia and T-cell lymphoma in adults.

  • Hunter Syndrome

    5 members

    Hunter Syndrome is a rare lysosomal storage disease caused by a deficient (or absent) enzyme, iduronate-2-sulfatase (I2S).

  • Huntington's Disease

    10 members

    Huntington's disease is a progressive brain disease characterized by the continuous loss of brain cells (neurons). Individuals with Huntington's Disea...

  • Hurler Syndrome

    31 members

    Hurler Syndrome is a rare disorder characterized by the buildup of mucopolysaccharides due to a deficiency of alpha-L iduronidase.

  • Hydrolethalus Syndrome


    Hydrolethalus Syndrome is a rare genetic disorder characterized by improper fetal development.

  • Hyperacusis

    1 members

    Hyperacusis is a rare hearing disorder that causes sounds which would otherwise seem normal to most people to sound unbearably loud. People who suffer from hyperacusis may even find normal envir...

  • Hyperemesis Gravidarum

    3 members

    Hyperemesis Gravidarum is a rare and severe form of morning sickness characterized by nausea and vomiting during pregnancy that may require hospitalization.

  • Hyperhidrosis

    4 members

    Hyperhidrosis is a rare disorder characterized by excessive sweating on the palms of the hands, the soles of the feet, in the armpits, in the groin area, and/or under the breasts.

  • Hyperkalemic Periodic Paralysis

    5 members

    Hyperkalemic Periodic Paralysis is a rare inherited autosomal dominant disorder.

  • Hyperlipoproteinemia

    1 members

    Hyperlipoproteinemia is the raised presence lipids in the blood.

  • Hyperoxaluria

    3 members

    Hyperoxaluria is a disorder characterized by excessive oxalate in the urine.

  • Hyperprolinemia

    3 members

    Hyperprolinemia is a condition which occurs when the amino acid proline is not broken down properly by the enzymes proline oxidase or pyrroline-5-carboxylate dehydrogense.

  • Hypersensitivity Pneumonitis

    1 members

    Hypersensitivity Pneumonitis is an inflammation of the lungs caused by hypersensitivity to inhaled organic dusts.

  • Hypochondroplasia

    1 members

    Hypochondroplasia is a developmental disorder classified as short-limbed dwarfism.

  • Hypokalemic Periodic Paralysis

    12 members

    Hypokalemic Periodic Paralysis is a rare disorder characterized by muscle weakness or paralysis.

  • Hypomagnesemia with secondary hypocalcemia

    3 members

    Hypomagnesemia with secondary hypocalcemia is an autosomal recessive genetic disorder affecting intestinal magnesium absorption.

  • Hypomyelination and Atrophy of the Basal Ganglia and the Cerebellum

    1 members

    H-ABC, for short.  Children and young adults with mutations of the TUBB4-4 gene.

  • Hypoparathyroidism

    5 members

    Hypoparathyroidism is a rare disorder in which your body secretes abnormally low levels of parathyroid hormone which plays a key role in regulating and maintaining a balance of your body's levels o...

  • Hypophosphatasia

    25 members

    Hypophosphatasia is a rare metabolic bone disorder characterized by decreased tissue nonspecific alkaline phosphatase and defective bone mineralization.