Pachygyria is a congenital malformation of the cerebral hemisphere causing developmental delay and seizures.

Human nerve cells are called neurons. The brain is made...

Pachyonychia Congenita is a rare genetic skin disorder.

Pallister-Hall Syndrome [PHS] is a multiple-anomaly rare genetic disorder caused by mutations in the GLI3 gene, short arm of the 7th Chromosome.

Pallister-Killian Syndrome is a rare genetic disorder occuring due to tetrasomy of the twelfth chromosome.

PANDAS is a rapid onset of obsessive-compulsive disorder after a group A β-hemolytic streptococcal infection.

Papillon–Lefevre Syndrome is a rare genetic disorder caused by a cathepsin C deficiency.

Paramyotonia Congenita is a rare neuromuscular disorder characterized by myotonia that becomes worse with exercise.

Paraneoplastic cerebellar degeneration is believed to be the body's immune system's attempt to destroy a tumor resulting in damage to the cerebellum.

Paraneoplastic Limbic Encephalitis is a form encephalitis caused by neoplasms associated with small cell lung carcinoma.

Parapsoriasis refers to a group of skin conditions that resemble psoriasis. Psoriasis is a skin disorder that leads to a rapid proliferation of skin cells that accumulate and form red and bumpy ...

Parkinson Disease is a progressive disorder of the nervous system.

Paroxysmal Kinesigenic Dyskinesia is a rare neurological disorder characterized by short, recurring attacks of involuntary movement, triggered by sudden voluntary movement.

Paroxysmal nocturnal hemoglobinuria is a rare blood disorder characterized by anemia due to destruction of red blood cells in the bloodstream, red urine, and thrombosis.

Parsonage-Turner Syndrome is a rare disorder affecting the motor neurons of nerves that conduct signals from the spine to the shoulder, arm, and hand.

Pelizaeus-Merzbacker Disease (PMD) is an inherited condition, passed on in an X-linked fashion, associated with impaired intellectual functions, limb spasticity and ataxia [1]. It affects the fo...

Pemphigus foliaceus is a rare autoimmune disease of the skin and mucous membranes with characteristic blisters that are scaly and crusted.

Pemphigus Vulgaris is a rare autoimmune skin disease that causes blisters. Most cases can be controlled with treatment, which consists of steroid medicines and other medicines to suppress the immun...

Pendred Syndrome is a rare genetic disorder causing hearing loss and a swollen thyroid gland.

Pentalogy of Cantrell is a rare disorder characterized by: Omphalocele; Anterior diaphragmatic hernia; Sternal cleft; Ectopia cordis; and Intracardiac defect.

Periodic Fever, Aphthous Stomatitis, Pharyngitis, and Adenitis (PFAPA) syndrome is the most common recurrent fever syndrome in children. The disease is characterized by cyclic fever episodes, mo...

Periventricular Heterotopia is a rare disorder where nerve cells do not situate properly during the early development of the fetal brain, potentially resulting in seizures and developmental delay.

Persistent Fetal Vasculature Syndrome is a rare disorder in which the lens of the eye is opaque and there is malformation of the retina.

Persistent Hyperinsulinemic Hypoglycemia of Infancy is a rare form of hypoglycemia characterized by severe recurrent hypoglycemia associated with an inappropriate elevation of serum insulin, C-pept...

Peutz-Jeghers Syndrome is a rare genetic disease characterized by the development of benign hamartomatous polyps in the gastrointestinal tract.

Pfeiffer Syndrome is a genetic disorder characterized by the premature fusion of bones of the skull.

Phenylketonuria (PKU) is an inherited metabolic disorder characterized by an inability to break down the amino acid phenylalanine found in proteins. In PKU, the enzyme phenylalanine hydroxylase ...

Pheochromocytomas and Paragangliomas (PPGLs) are rare neuroendocrine tumors that derive from an embryonic ridge-like structure known as the neural crest. Cells that comprise these tumors are kno...

Piebaldism is a rare autosomal dominant disorder of melanocyte development characterized by a congenital white forelock and multiple symmetrical hypopigmented or depigmented macules.

Pierre Robin Sequence is a chain of certain developmental malformations.

Pigmented Villonodular Synovitis is a rare joint disorder that generally affects the hip and knee, but can also occur in the shoulder, ankle, elbow, hand and foot.

Pilocytic Astrocytoma is a brain tumor that occurs predominantly in children.

Piriformis Syndrome is a disorder in which the sciatic nerve is compressed by the piriformis muscle.

Pitt-Hopkins Syndrome is a very rare genetic disorder characterized mainly by psychomotor delay and in some individuals periods of apnea and/or seizures.

Pityriasis Rubra Pilaris is a group of rare skin disorders characterized by reddish orange patches on the skin and severe flaking.

Plasminogen Deficiency is a rare blood disorder related to blood clots that typically only causes eye problems.

POEMS Syndrome is a rare disorder named for its main features: Polyneuropathy (peripheral nerve damage), Organomegaly (abnormal enlargement of organs), Endocrinopathy (damage to hormone-producing ...

Poland syndrome is a rare congenital condition characterized by the underdevelopment or absence of muscles on one side of the chest, often accompanied by hand abnormalities on the same side. It ...

Polyarteritis Nodosa is inflammation of medium-sized arteriesdue to attacks by rogue immune cells.

Polycythemia Vera is a rare blood disorder characterized by excess red blood cells caused by an abnormality of the bone marrow.

Polydactyly Preaxial is a congenital physical anomaly consisting of additional fingers.

Polymyalgia Rheumatica is an inflammatory condition of the muscles characterized by pain or stiffness.

Polymyositis (PM) is an idiopathic inflammatory myopathy, meaning an inflammation of the muscles without a known cause. The immune system is the body’s defense against foreign ma...

Polysplenia syndrome is a disorder characterized by multiple small spleens in the abdominal cavity with absence of the normally located spleen; visceral lateralization and congenital heart malforma...

Pontocerebellar Hypoplasia is a group of rare degenerative neurological disorders resulting in the atrophy of the cerebellar cortex.

Porphyria Cutanea Tarda is the most common subtype of resulting in the blistering of the skin when exposed to sunlight.

Postural Orthostatic Tachycardia Syndrome (POTS) is a complex medical condition characterized by an abnormally large increase in heart rate upon standing. It belongs to a broader category of dis...

Potocki-Lupski Syndrome is the result of the duplication of chromosome 17p11.2.

Potocki-Shaffer Syndrome is a rare genetic disorder resulting from the microdeletion of section 11.2 on the short arm of chromosome 11.

Prader-Willi Syndrome is the most common genetic cause of life-threatening morbid obesity.

Primary Angiitis of the Central Nervous System is a disorder that affects the blood vessels in the central nervous system.

Primary Biliary Cholangitis (or PBC) is a chronic and progressive liver disease resulting from the slowly destruction of the liver bile ducts.  Among other substances the liver pr...

Primary Ciliary Dyskinesia (PCD) is a rare, inherited genetic disorder characterized by defects in the structure and function of cilia—microscopic, hair-like structures that line the respi...

Primary Idiopathic Cold Urticaria is a non-genetic rare inflammatory disorder characterized by fever and rash after generalized exposure to cold temperatures.

Primary Intestinal Lymphangiectasia is a rare disorder causing protein to be lost from the intestines due to enlarged lymph vessels that supply the lining of the small intestine.

Primary lateral sclerosis is a rare neuromuscular disease.

Primary Lymphedema is a rare, inherited, disorder characterized by abnormal formations of lymphatic vessels before birth.

Primary Orthostatic Tremor is a rare disorder characterized by tremors of the legs.

Primary Sclerosing Cholangitis (PSC) is a rare disorder that damages and blocks bile ducts inside and outside the liver.

Prinzmetal's Angina is a disorder characterized by cycles of angina (cardiac chest pain) at when resting.

Progeria, or Hutchinson-Gilford Progeria Syndrome, is a rare, fatal, “premature aging” disease that afflicts children, who die of atherosclerosis (heart disease) at an average age of thirteen years...

Progressive Familial Intrahepatic Cholestasis is a rare, severe, and genetically inherited liver disease in which the flow of bile from the liver is blocked even though the bile ducts are open. Bil...

Progressive Multifocal Leucoencephalopathy is a disease of the brain's white matter.

Progressive Supranuclear Palsy is a rare degenerative disorder involving the gradual deterioration and death of selected areas of the brain.

Propionic Acidemia is a rare autosomal recessive metabolic disorder characterized by deficiency of propionyl CoA carboxylase.

Prune belly syndrome is a rare birth defect of the urinary system, characterized by a triad of symptoms.

Prurigo nodularis is a skin disease characterized by itchy lumps, which usually appear on the arms or legs.

Pseudohypoaldosteronism refers to a heterogeneous group of disorders of electrolyte metabolism characterized by an apparent state of renal tubular unresponsiveness or resistance to the action of al...

Pseudoxanthoma Elasticum is a rare genetic disease characterized by the fragmentation and mineralization of elastic fibers in some tissues.

Psoriasis is a chronic autoimmune system condition that is commonly considered an inflammatory skin disease. Psoriasis causes a rapid expansion of skin cells that leads to the formation of painf...

Psoriatic Arthritis is a type of inflammatory arthritis affects around10-15% of people suffering from psoriasis.

Pterygium is a rare medical disorder characterized by a benign, elevated, superficial, external ocular mass that usually forms over the perilimbal conjunctiva and extends onto the corneal surface.*

Pulmonary Alveolar Microlithiasis is a rare disorder characterized by the deposition of calcium phosphate microliths in the lungs.

Pulmonary Alveolar Proteinosis is a rare lung disorder characterized with abnormal accumulation of surfactant in the alveoli.

Pulmonary Arterial Hypertension is consistantly high blood pressure in the pulmonary artery.

Pulmonary Valve Stenosis is a rare valvular heart disorder.

Pure Autonomic Failure is a rare disorder involving the malfunction of the autonomic nervous system.

Pyoderma gangrenosum (PG) is a rare non-infectious, autoinflammatory condition characterized by painful, rapidly expanding skin ulcers with violet-colored irregular edges. It typically occurs in...