Ankyloglossia, also known as tongue-tie, is a condition in which the lingual frenulum (the band of tissue that connects the bottom of the tongue to the floor of the mouth) is shorter than normal, restricting the movement of the tongue. This can ca...

Anodontia is a rare genetic disorder characterized by the complete absence of teeth. It can affect both primary (baby) teeth and permanent teeth. Anodontia can be either isolated, meaning it occurs on its own, or it can be part of a syndrome that ...

Asperger’s syndrome, though no longer an official diagnosis, belongs to a group of neurodevelopment conditions known as autism spectrum disorder (ASD). Experts consider what was previously diagnosed as Asperger’s syndrome t...

OverviewArteriosclerosis occurs when the blood vessels that carry oxygen and nutrients from your heart to the rest of your body (arteries) become thick and stiff — sometimes restricting blood flow to your organs and tissues. Healthy art...

Arteriosclerosis occurs when the blood vessels that carry oxygen and nutrients from your heart to the rest of your body (arteries) become thick and stiff — sometimes restricting blood flow to your organs and tissues. Healthy arteries are fle...

What is brain cancer? Brain cancer is a disease of the brain in which cancer cells (malignant cells) arise in the brain tissue. Cancer cells grow to form a mass of cancer tissue (tumor) that interferes with brain functions such as muscle c...

A brain tumor is a mass or growth of abnormal cells in your brain. Many different types of brain tumors exist. Some brain tumors are noncancerous (benign), and some brain tumors are cancerous (malignant). Brain tumors can begin in your bra...

Fukuyama type congenital muscular dystrophy (FCMD) is one of several forms of a rare type of muscular dystrophy known as congenital muscular dystrophy. It is inherited as an autosomal recessive trait. Symptoms of this disorder are apparent at birt...

Simpson dysmorphia syndrome types 1 and 2 are two forms of a rare, X-linked recessive, inherited disorder characterized by unusually large fetuses (prenatal overgrowth) and unusually large babies (postnatal overgrowth). In addition, affected indiv...

Cerebral palsy facts Cerebral palsy (CP) is an abnormality of motor function, the ability to move and control movements. Cerebral palsy is acquired at an early age, usually less than a year of age. Cerebral palsy...

Chromosome 22q11.2 deletion syndrome is associated with a range of problems including: congenital heart disease, palate abnormalities, immune system dysfunction including autoimmune disease, low calcium (hypocalcemia) and other endocrine abnormali...

Crossbite is a dental condition in which the upper teeth do not align properly with the lower teeth when the jaw is closed. This misalignment can occur on one side of the mouth (unilateral crossbite) or on both sides (bilateral crossbite). Crossbi...

Croup is a common childhood illness that causes swelling of the upper respiratory tract. This can be recognised by a change in tone of voice and a distinctive "croupy" cough that sounds like a seal or barking. Croup is caused by a variety of virus...

Crowded teeth, also known as dental crowding, is a common orthodontic issue where there is not enough space in the mouth for all of the teeth to align properly. This can result in teeth overlapping, twisting, or becoming crooked. Crowded teeth can...

General DiscussionJervell and Lange-Nielsen syndrome (JLNS) is a rare inherited disorder characterized by deafness present at birth (congenital) occurring in association with abnormalities affecting the electrical system of the heart. The...

Determining hearing loss in children facts Children can be tested for hearing loss at any age. There are several risk factors associated with hearing loss, including ear infections, prematurity, diseases, and syndromes....

Sjogren-Larsson syndrome is an inherited disorder characterized by scaling skin (ichthyosis), mental retardation, speech abnormalities, and spasticity. Affected infants develop various degrees of reddened skin with fine scales soon after birth. Af...

The hereditary ataxias are a group of neurological disorders (ataxias) of varying degrees of rarity that are inherited, in contrast to a related group of neurological disorders that are acquired through accidents, injuries, or other external agent...

Friedreich's Ataxia is a genetic, progressive, neurologic movement disorder that typically becomes apparent before adolescence. Initial symptoms may include unsteady posture, frequent falling, and progressive difficulties walking due to an impaire...

Frontotemporal dementia (FTD), or Pick's disease, is a syndrome featuring shrinking of the frontal and temporal anterior lobes of the brain. The symptoms of frontotemporal dementia fall into two clinical patterns that involve either...

  Frontotemporal dementia (FTD), or Pick's disease, is a syndrome featuring shrinking of the frontal and temporal anterior lobes of the brain. The symptoms of frontotemporal dementia fall into two clinical patterns th...

Fukuyama type congenital muscular dystrophy (FCMD) is one of several forms of a rare type of muscular dystrophy known as congenital muscular dystrophy. It is inherited as an autosomal recessive trait. Symptoms of this disorder are apparent at birt...

Gaps between teeth, also known as diastema, are spaces or openings between two or more teeth. These gaps can occur anywhere in the mouth but are most commonly seen between the two upper front teeth. Gaps between teeth can be caused by a variety of...

Erythrokeratodermia with ataxia (EKDA) is a hereditary disorder of the skin and nervous system (neurocutaneous syndrome) characterized by groups of hard, red plaques that develop during infancy and childhood. When these skin lesions heal, the diso...

Chromosome 10, monosomy 10p is a rare chromosomal disorder in which the end (distal) portion of the short arm (p) of chromosome 10 is missing (deleted or monosomic). The range and severity of symptoms and findings may be variable, depending upon t...

Hartnup disease is a rare metabolic disorder inherited as an autosomal recessive trait. It involves an inborn error of amino acid metabolism as well as niacin deficiency. Factors that may precipitate acute attacks of this disorder may include poor...

Hartnup disease is a rare metabolic disorder inherited as an autosomal recessive trait. It involves an inborn error of amino acid metabolism as well as niacin deficiency. Factors that may precipitate acute attacks of this disorder may include poor...

Hypodontia, also known as missing teeth, is a condition in which a person is born with fewer teeth than the normal number. This can affect both primary (baby) teeth and permanent teeth. Hypodontia can range from the absence of just one tooth to mu...

Sjogren-Larsson syndrome is an inherited disorder characterized by scaling skin (ichthyosis), mental retardation, speech abnormalities, and spasticity. Affected infants develop various degrees of reddened skin with fine scales soon after birth. Af...

Sjogren-Larsson syndrome is an inherited disorder characterized by scaling skin (ichthyosis), mental retardation, speech abnormalities, and spasticity. Affected infants develop various degrees of reddened skin with fine scales soon after birth. Af...

Cri du chat syndrome (CdCS or 5p-) is a rare genetic disorder in which a variable portion of the short arm of chromosome 5 is missing or deleted (monosomic). Symptoms vary greatly from case to case depending upon the exact size and location of the...

Chanarin Dorfman syndrome is a rare hereditary disorder of fat (lipid) metabolism. It is characterized by scaly skin (ichthyosis), degeneration of the muscles (myopathy), and abnormal white blood cells with small spaces (vacuoles) filled with fat ...

Ataxia telangiectasia (AT) is a complex genetic neurodegenerative disorder that may become apparent during infancy or early childhood. The disorder is characterized by progressively impaired coordination of voluntary movements (ataxia), the develo...

Androgen insensitivity refers to an inability of the body to respond properly to male sex hormones (androgens) produced during pregnancy. This occurs because of a change (mutation) in a gene involved in the production of the protein inside cells t...

Malocclusion is a dental condition in which the teeth are misaligned or do not fit together properly when the jaws are closed. This can result in problems with biting, chewing, and speaking, as well as issues with the appearance of the teeth and f...

Microcephaly is a condition where the head (circumference) is smaller than normal. Microcephaly may be caused by genetic abnormalities or by drugs, alcohol, certain viruses, and toxins that are exposed to the fetus during pregnancy ...

Motor neuron disease comprises a group of severe disorders of the nervous system characterized by progressive degeneration of motor neurons (neurons are the basic nerve cells that combine to form nerves). Motor neurons control the behavior of musc...

Moyamoya syndrome is a progressive disorder that affects the blood vessels in the brain (cerebrovascular). It is characterized by the narrowing (stenosis) and/or closing (occlusion) of the carotid artery inside the skull, the major artery that del...

Moyamoya syndrome is a progressive disorder that affects the blood vessels in the brain (cerebrovascular). It is characterized by the narrowing (stenosis) and/or closing (occlusion) of the carotid artery inside the skull, the major artery that del...

The Mucopolysaccharidoses (MPS Disorders) are a group of rare genetic disorders caused by the deficiency of one of the lysosomal enzymes, resulting in an inability to metabolize complex carbohydrates (mucopolysaccharides) into simpler molecules. H...

Multiple sclerosis (MS) is a disease that causes demyelination (disruption of the myelin that insulates and protects nerve cells) of spinal nerve and brain cells. Although the exact case is unknown, multiple sclerosis is considered ...

Open bite is a type of malocclusion (misalignment of the teeth) where the upper and lower front teeth do not touch when the mouth is closed. This can be caused by a variety of factors, including genetics, thumb sucking, tongue thrusting, or prolon...

Oral hyperplasia is a condition characterized by an abnormal increase in the size of the tissues in the mouth. This can occur in the gums, tongue, cheeks, or other areas of the oral cavity. It can be caused by a variety of factors, including infla...

Oral Myofunctional Disorder (OMD) is a condition that affects the muscles and functions of the mouth and face. It can involve abnormal patterns of muscle movement during activities such as swallowing, speaking, and breathing. OMD can lead to a var...

An overbite is a dental condition in which the upper front teeth overlap significantly with the lower front teeth when the mouth is closed. This can be caused by genetics, thumb sucking, or prolonged use of a pacifier. Overbites can lead to issues...

Phelan-McDermid syndrome is a rare chromosomal disorder in which a portion of the long arm (q) of chromosome 22 is missing (deleted or monosomic). Although the range and severity of symptoms may vary, Phelan-McDermid syndrome is generally thought ...

Frontotemporal dementia (FTD), or Pick's disease, is a syndrome featuring shrinking of the frontal and temporal anterior lobes of the brain. The symptoms of frontotemporal dementia fall into two clinical patterns that involve either...

Psychotic disorders include schizophrenia and a number of lesser-known disorders. The number of people who develop a psychotic disorder tends to vary depending on the country, age, and gender of the sufferer, as well as on the speci...

Sydenham chorea is a rare neurological disorder characterized by rapid, involuntary, purposeless movements, especially of the face, feet and hands. Additional symptoms may include muscle weakness and emotional or behavioral problems. Sydenham chor...

Rubinstein-Taybi syndrome is a rare genetic multisystem disorder that affects many organ systems of the body. The group of findings (constellation) associated with this syndrome include growth retardation and delayed bone age; mental retardation; ...

Sialorrhea, also known as drooling, is the excessive production of saliva that results in saliva spilling out of the mouth. It can be caused by a variety of factors, including neurological conditions, developmental delays, medications, or problems...

Friedreich's Ataxia is a genetic, progressive, neurologic movement disorder that typically becomes apparent before adolescence. Initial symptoms may include unsteady posture, frequent falling, and progressive difficulties walking due to an impaire...

The hereditary ataxias are a group of neurological disorders (ataxias) of varying degrees of rarity that are inherited, in contrast to a related group of neurological disorders that are acquired through accidents, injuries, or other external agent...

Subacute cerebellar degeneration (SCD) is characterized by the deterioration of the area of the brain concerned with muscle coordination and balance (the cerebellum). Less frequently, the area involved may include the area connecting the spinal co...

Succinic semialdehyde dehydrogenase (SSADH) deficiency is a rare inborn error of metabolism that is inherited as an autosomal recessive trait. In individuals with the disorder, deficient activity of the SSADH enzyme disrupts the metabolism of gamm...

Tongue thrusting is a swallowing pattern in which the tongue pushes forward against the front teeth when swallowing, rather than pressing up against the roof of the mouth. This can lead to dental issues such as an open bite, speech problems, and d...

Tongue-tie, also known as ankyloglossia, is a condition in which the thin piece of skin under the baby's tongue (lingual frenulum) is shorter than usual. This can restrict the movement of the tongue, making it difficult for the baby to breastfeed ...

Dystonia is a group of movement disorders that vary in their symptoms, causes, progression, and treatments. This group of neurological conditions is generally characterized by involuntary muscle contractions that force the body into abnormal, some...

Treacher Collins syndrome (TCS) is a rare genetic disorder characterized by distinctive abnormalities of the head and face area resulting from underdevelopment (hypoplasia) of certain facial structures including the jaw, cheekbones and nearby stru...

An underbite is a dental condition in which the lower teeth protrude further out than the upper teeth when the jaw is closed. This misalignment of the teeth can cause issues with chewing, speaking, and overall oral health. Underbites can be caused...

Joubert syndrome is an autosomal recessive genetic disorder that affects the area of the brain that controls balance and coordination. This condition is characterized by a specific finding on an MRI called a "molar tooth sign" in which the cerebel...

MCT8-specific thyroid hormone cell transporter deficiency (THCT deficiency) is an inherited disorder that is characterized by severe mental retardation, an impaired ability to speak, diminished muscle tone (hypotonia), and/or movement abnormalitie...

L1 syndrome is an inherited, X-linked disorder occurring in males that primarily affects the nervous system. The disease is mainly characterized by hydrocephalus (increased fluid in the center of the brain), spasticity of the lower limbs (muscle s...