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...

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...

Camptomelic syndrome is a rare congenital disorder in which multiple anomalies are present. It is characterized by bowing and angular shape of the long bones of the legs, especially the tibia; multiple minor anomalies of the face; cleft palate; ot...

Congenital hypomyelination neuropathy (CHN) is a neurological disorder present at birth. Major symptoms may include respiratory difficulty, muscle weakness and incoordination, poor muscle tone (neonatal hypotonia), absence of reflexes (areflexia),...

Congenital hypomyelination neuropathy (CHN) is a neurological disorder present at birth. Major symptoms may include respiratory difficulty, muscle weakness and incoordination, poor muscle tone (neonatal hypotonia), absence of reflexes (areflexia),...

Cutis laxa is rarely encountered and may occur in several inherited (congenital) forms or come about in the course of another disorder (acquired). It is a connective tissue disorder characterized by skin that is loose (lax), hanging, wrinkled, and...

De Barsy syndrome is a rare, autosomal recessive genetic disorder, the main characteristics of which are a prematurely aged-looking face (progeria), cloudy corneas, short stature, and mental retardation. The condition is expressed in variable pres...

Down syndrome is a genetic disorder and the most common autosomal chromosome abnormality in humans, where extra genetic material from chromosome 21 is transferred to a newly formed embryo. These extra genes and DNA cause changes in the development...

Biotinidase deficiency (BTD) is a treatable, metabolic disorder that is the result of a low concentration, or complete lack, of the enzyme, biotinidase. Biotinidase deficiency is an inherited disorder in which the body is not able to properly proc...

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 spinal muscular atrophies (SMAs), are characterized by degeneration of nerve cells (motor nuclei) within the lowest region of the brain (lower brainstem) and certain motor neurons in the spinal cord (anterior horn cells) leading to muscle weak...

The spinal muscular atrophies (SMAs), are characterized by degeneration of nerve cells (motor nuclei) within the lowest region of the brain (lower brainstem) and certain motor neurons in the spinal cord (anterior horn cells) leading to muscle weak...

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...

Chromosome 18, Monosomy 18p is a rare chromosomal disorder in which all or part of the short arm (p) of chromosome 18 is deleted (monosomic). The disorder is typically characterized by short stature, variable degrees of mental retardation, speech ...

Prader-Willi syndrome (PWS) is a genetic multisystem disorder characterized during infancy by lethargy, diminished muscle tone (hypotonia), feeding difficulties, and poor weight gain. In childhood, features of this disorder include short stature, ...

Familial dysautonomia is a rare genetic disorder of the autonomic nervous system (ANS) that primarily affects people of Eastern European Jewish heritage. It is characterized by diminished sensitivity to pain, lack of overflow tearing in the eyes, ...