FGFR1 Gene

Encephalocraniocutaneous lipomatosis (ECCL) is a rare condition that primarily affects the brain, eyes, and skin of the head and face. Most of this condition's signs and symptoms are present from birth, and they vary widely among affected individuals.

A hallmark feature of ECCL is a noncancerous tumor under the scalp covered by a smooth, hairless patch of skin. This type of tumor, called a nevus psiloliparus, is made up of fatty tissue. Some people with ECCL also have noncancerous tumors under the skin elsewhere on the head or face. Many have small flaps of skin called skin tags on the eyelids and around the eyes. Hair loss (alopecia), thin or missing patches of skin on the scalp (dermal hypoplasia or aplasia), and changes in skin coloring (pigmentation) are also possible.

The most common eye abnormality in ECCL is a noncancerous growth called a choristoma. These growths can be present in one or both eyes and may affect vision.

About two-thirds of people with ECCL have noncancerous fatty tumors inside the brain or around the spinal cord. These tumors are called intracranial lipomas and intraspinal lipomas, respectively. Affected individuals also have an increased risk of developing a type of brain cancer called a glioma. The brain and spinal cord abnormalities associated with ECCL can cause seizures, abnormal tensing of the muscles, and intellectual disability ranging from mild to profound. However, about one-third of affected individuals have normal intelligence.

Other kinds of growths may also occur in people with ECCL, including noncancerous jaw tumors.

Pfeiffer syndrome is a genetic disorder characterized by the premature fusion of certain skull bones (craniosynostosis). This early fusion prevents the skull from growing normally and affects the shape of the head and face. Pfeiffer syndrome also affects bones in the hands and feet.

Many of the characteristic facial features of Pfeiffer syndrome result from premature fusion of the skull bones. Abnormal growth of these bones leads to bulging and wide-set eyes, a high forehead, an underdeveloped upper jaw, and a beaked nose. More than half of all children with Pfeiffer syndrome have hearing loss; dental problems are also common.

In people with Pfeiffer syndrome, the thumbs and first (big) toes are wide and bend away from the other digits. Unusually short fingers and toes (brachydactyly) are also common, and there may be some webbing or fusion between the digits (syndactyly).

Pfeiffer syndrome is divided into three subtypes. Type 1, also known as classic Pfeiffer syndrome, has symptoms as described above. Most individuals with type 1 Pfeiffer syndrome have normal intelligence and a normal life span. Types 2 and 3 are more severe forms of Pfeiffer syndrome that often involve problems with the nervous system. The premature fusion of skull bones can limit brain growth, leading to delayed development and other neurological problems. In addition, individuals with type 2 or 3 can have fusion of the bones (ankylosis) in the elbow or other joints, limiting mobility, and abnormalities of the face and airways, which can cause life-threatening breathing problems. Type 2 is distinguished from type 3 by the presence of a cloverleaf-shaped head, which is caused by more extensive fusion of bones in the skull.

Kallmann syndrome is a condition characterized by delayed or absent puberty and an impaired sense of smell.

This disorder is a form of hypogonadotropic hypogonadism, which is a condition resulting from a lack of production of certain hormones that direct sexual development. These hormones are normally made in a part of the brain called the hypothalamus. Males born with hypogonadotropic hypogonadism often have an unusually small penis (micropenis) and undescended testes (cryptorchidism). At puberty, most affected individuals do not develop secondary sex characteristics, such as the growth of facial hair and deepening of the voice in males, the start of monthly periods (menstruation) and breast development in females, and a growth spurt in both sexes. Without treatment, most affected men and women are unable to have biological children (infertile).

In Kallmann syndrome, the sense of smell is either diminished (hyposmia) or completely absent (anosmia). This feature distinguishes Kallmann syndrome from most other forms of hypogonadotropic hypogonadism, which do not affect the sense of smell. Many people with Kallmann syndrome are not aware that they are unable to detect odors until the impairment is discovered through testing.

Kallmann syndrome can have a wide variety of additional signs and symptoms. These include a failure of one kidney to develop (unilateral renal agenesis), abnormalities of bones in the fingers or toes, a cleft lip with or without an opening in the roof of the mouth (a cleft palate), abnormal eye movements, hearing loss, and abnormalities of tooth development. Some affected individuals have a feature called bimanual synkinesis, in which the movements of one hand are mirrored by the other hand. Bimanual synkinesis can make it difficult to do tasks that require the hands to move separately, such as playing a musical instrument.

Jackson-Weiss syndrome is a genetic disorder characterized by foot abnormalities and the premature fusion of certain skull bones (craniosynostosis). This early fusion prevents the skull from growing normally and affects the shape of the head and face.

Many of the characteristic facial features of Jackson-Weiss syndrome result from premature fusion of the skull bones. Abnormal growth of these bones leads to a misshapen skull, widely spaced eyes, and a bulging forehead.

Foot abnormalities are the most consistent features of Jackson-Weiss syndrome. The first (big) toes are short and wide, and they bend away from the other toes. Additionally, the bones of some toes may be fused together (syndactyly) or abnormally shaped. The hands are almost always normal.

Some individuals with Jackson-Weiss syndrome have hearing impairment. People with Jackson-Weiss syndrome usually have normal intelligence and a normal life span.

Hartsfield syndrome is a rare condition characterized by holoprosencephaly, which is an abnormality of brain development, and a malformation of the hands and feet called ectrodactyly.

During early development before birth, the brain normally divides into two halves, the right and left hemispheres. Holoprosencephaly occurs when the brain fails to divide properly. In the most severe forms of holoprosencephaly, the brain does not divide at all. These affected individuals have one central eye (cyclopia) and a tubular nasal structure (proboscis) located above the eye. Most babies with severe holoprosencephaly die before birth or soon after. In less severe cases of holoprosencephaly, the brain is partially divided. The life expectancy of these affected individuals depends on the severity of signs and symptoms.

People with Hartsfield syndrome often have other brain abnormalities associated with holoprosencephaly. Affected individuals may have a malfunctioning pituitary, which is a gland located at the base of the brain that produces several hormones. Because pituitary dysfunction leads to the partial or complete absence of these hormones, it can cause a variety of disorders. These include diabetes insipidus, which disrupts the balance between fluid intake and urine excretion; a shortage (deficiency) of growth hormone, leading to slow or delayed growth; and hypogonadotropic hypogonadism, which affects the production of hormones that direct sexual development. Dysfunction in other parts of the brain can cause seizures, feeding difficulties, and problems regulating body temperature and sleep patterns. People with Hartsfield syndrome have delayed development that ranges from mild to severe.

The other hallmark feature of Hartsfield syndrome is ectrodactyly. Ectrodactyly is a deep split in the hands, feet, or both, with missing fingers or toes and partial fusion of the remaining digits. It can affect the hands and feet on one or both sides. Other features that have been described in people with Hartsfield syndrome include premature fusion of certain bones of the skull (craniosynostosis), heart defects, abnormalities of the bones of the spine (vertebrae), and abnormal genitalia. Some affected individuals have distinctive facial features, including eyes that are widely spaced (hypertelorism) or closely spaced (hypotelorism), ears that are abnormally small or unusually shaped, and a split in the lip (cleft lip) with or without an opening in the roof of the mouth (cleft palate).

Osteoglophonic dysplasia is a condition characterized by abnormal bone growth that leads to severe head and face (craniofacial) abnormalities, dwarfism, and other features. The term osteoglophonic refers to the bones (osteo-) having distinctive hollowed out (-glophonic) areas that appear as holes on x-ray images.

Premature fusion of certain bones in the skull (craniosynostosis) typically occurs in osteoglophonic dysplasia. The craniosynostosis associated with this disorder may give the head a tall appearance, often referred to in the medical literature as a tower-shaped skull, or a relatively mild version of a deformity called a cloverleaf skull. Characteristic facial features in people with osteoglophonic dysplasia include a prominent forehead (frontal bossing), widely spaced eyes (hypertelorism), flattening of the bridge of the nose and of the middle of the face (midface hypoplasia), a large tongue (macroglossia), a protruding jaw (prognathism), and a short neck. People with this condition usually have no visible teeth because the teeth never emerge from the jaw (clinical anodontia). In addition, the gums are often overgrown (hypertrophic gingiva).

Infants with osteoglophonic dysplasia often experience failure to thrive, which means they do not gain weight and grow at the expected rate. Affected individuals have short, bowed legs and arms and are short in stature. They also have flat feet and short, broad hands and fingers.

The life expectancy of people with osteoglophonic dysplasia depends on the extent of their craniofacial abnormalities; those that obstruct the air passages and affect the mouth and teeth can lead to respiratory problems and cause difficulty with eating and drinking. Despite the skull abnormalities, intelligence is generally not affected in this disorder.

Kallmann syndrome is a condition characterized by delayed or absent puberty and an impaired sense of smell.

This disorder is a form of hypogonadotropic hypogonadism, which is a condition resulting from a lack of production of certain hormones that direct sexual development. These hormones are normally made in a part of the brain called the hypothalamus. Males born with hypogonadotropic hypogonadism often have an unusually small penis (micropenis) and undescended testes (cryptorchidism). At puberty, most affected individuals do not develop secondary sex characteristics, such as the growth of facial hair and deepening of the voice in males, the start of monthly periods (menstruation) and breast development in females, and a growth spurt in both sexes. Without treatment, most affected men and women are unable to have biological children (infertile).

In Kallmann syndrome, the sense of smell is either diminished (hyposmia) or completely absent (anosmia). This feature distinguishes Kallmann syndrome from most other forms of hypogonadotropic hypogonadism, which do not affect the sense of smell. Many people with Kallmann syndrome are not aware that they are unable to detect odors until the impairment is discovered through testing.

Kallmann syndrome can have a wide variety of additional signs and symptoms. These include a failure of one kidney to develop (unilateral renal agenesis), abnormalities of bones in the fingers or toes, a cleft lip with or without an opening in the roof of the mouth (a cleft palate), abnormal eye movements, hearing loss, and abnormalities of tooth development. Some affected individuals have a feature called bimanual synkinesis, in which the movements of one hand are mirrored by the other hand. Bimanual synkinesis can make it difficult to do tasks that require the hands to move separately, such as playing a musical instrument.

Nonsyndromic holoprosencephaly is an abnormality of brain development that also affects the head and face. Normally, the brain divides into two halves (hemispheres) during early development. Holoprosencephaly occurs when the brain fails to divide properly into the right and left hemispheres. This condition is called nonsyndromic to distinguish it from other types of holoprosencephaly caused by genetic syndromes, chromosome abnormalities, or substances that cause birth defects (teratogens). The severity of nonsyndromic holoprosencephaly varies widely among affected individuals, even within the same family.

Nonsyndromic holoprosencephaly can be grouped into four types according to the degree of brain division. From most to least severe, the types are known as alobar, semi-lobar, lobar, and middle interhemispheric variant (MIHV). In the most severe forms of nonsyndromic holoprosencephaly, the brain does not divide at all. These affected individuals have one central eye (cyclopia) and a tubular nasal structure (proboscis) located above the eye. Most babies with severe nonsyndromic holoprosencephaly die before birth or soon after. In the less severe forms, the brain is partially divided and the eyes are usually set close together (hypotelorism). The life expectancy of these affected individuals varies depending on the severity of symptoms.

People with nonsyndromic holoprosencephaly often have a small head (microcephaly), although they can develop a buildup of fluid in the brain (hydrocephalus) that causes increased head size (macrocephaly). Other features may include an opening in the roof of the mouth (cleft palate) with or without a split in the upper lip (cleft lip), one central front tooth instead of two (a single maxillary central incisor), and a flat nasal bridge. The eyeballs may be abnormally small (microphthalmia) or absent (anophthalmia).

Some individuals with nonsyndromic holoprosencephaly have a distinctive pattern of facial features, including a narrowing of the head at the temples, outside corners of the eyes that point upward (upslanting palpebral fissures), large ears, a short nose with upturned nostrils, and a broad and deep space between the nose and mouth (philtrum). In general, the severity of facial features is directly related to the severity of the brain abnormalities. However, individuals with mildly affected facial features can have severe brain abnormalities. Some people do not have apparent structural brain abnormalities but have some of the facial features associated with this condition. These individuals are considered to have a form of the disorder known as microform holoprosencephaly and are typically identified after the birth of a severely affected family member.

Most people with nonsyndromic holoprosencephaly have developmental delay and intellectual disability. Affected individuals also frequently have a malfunctioning pituitary gland, which is a gland located at the base of the brain that produces several hormones. Because pituitary dysfunction leads to the partial or complete absence of these hormones, it can cause a variety of disorders. Most commonly, people with nonsyndromic holoprosencephaly and pituitary dysfunction develop diabetes insipidus, a condition that disrupts the balance between fluid intake and urine excretion. Dysfunction in other parts of the brain can cause seizures, feeding difficulties, and problems regulating body temperature, heart rate, and breathing. The sense of smell may be diminished (hyposmia) or completely absent (anosmia) if the part of the brain that processes smells is underdeveloped or missing.