Hypochondroplasia
Encyclopedia
Hypochondroplasia is a developmental disorder caused by an autosomal dominant genetic defect in the fibroblast growth factor receptor
3 gene (FGFR3
) that results in a disproportionately short stature, micromelia, and a head that appears large when compared with the underdeveloped portions of the body. It is also known as "achondroplasia tarda" and "atypical achondroplasia."
It is classified as short-limbed dwarfism
.
. As the infant grows, however, their arms and legs do not develop properly and their body becomes thicker and shorter than normal. The head is normal but appears large due to the underdevelopment of other parts of the body, a symptom called "relative macrocephaly
".
The clinical and radiographic features of this disorder are milder than those seen in achondroplasia
.
Intelligence
is usually normal.
domain of the FGFR3 gene. This gene plays an important role in embryonic development
, playing a part in regulating activities such as cell division, migration, and differentiation.
and physical therapy
. Genetic counseling
is advised for patients and their families.
4p16.3.
There is no cure for this condition.
Fibroblast growth factor receptor
The fibroblast growth factor receptors are, as their name implies, receptors that bind to members of the fibroblast growth factor family of proteins. Some of these receptors are involved in pathological conditions...
3 gene (FGFR3
FGFR3
Fibroblast growth factor receptor 3 is a protein that in humans is encoded by the FGFR3 gene. FGFR3 has also been designated as CD333 .-Structure and function:-Disease linkage:...
) that results in a disproportionately short stature, micromelia, and a head that appears large when compared with the underdeveloped portions of the body. It is also known as "achondroplasia tarda" and "atypical achondroplasia."
It is classified as short-limbed dwarfism
Dwarfism
Dwarfism is short stature resulting from a medical condition. It is sometimes defined as an adult height of less than 4 feet 10 inches , although this definition is problematic because short stature in itself is not a disorder....
.
Features
People affected by this disorder appear normal at birthBirth
Birth is the act or process of bearing or bringing forth offspring. The offspring is brought forth from the mother. The time of human birth is defined as the time at which the fetus comes out of the mother's womb into the world...
. As the infant grows, however, their arms and legs do not develop properly and their body becomes thicker and shorter than normal. The head is normal but appears large due to the underdevelopment of other parts of the body, a symptom called "relative macrocephaly
Macrocephaly
Macrocephaly , occurs when the head is abnormally large; this includes the scalp, the cranial bone, and the contents of the cranium.-Causes:...
".
The clinical and radiographic features of this disorder are milder than those seen in achondroplasia
Achondroplasia
Achondroplasia dwarfism occurs as a sporadic mutation in approximately 85% of cases or may be inherited in an autosomal dominant genetic disorder that is a common cause of dwarfism...
.
Intelligence
Intelligence
Intelligence has been defined in different ways, including the abilities for abstract thought, understanding, communication, reasoning, learning, planning, emotional intelligence and problem solving....
is usually normal.
Pathophysiology
This disorder results from mutations in the proximal tyrosine kinaseTyrosine kinase
A tyrosine kinase is an enzyme that can transfer a phosphate group from ATP to a protein in a cell. It functions as an "on" or "off" switch in many cellular functions....
domain of the FGFR3 gene. This gene plays an important role in embryonic development
Embryogenesis
Embryogenesis is the process by which the embryo is formed and develops, until it develops into a fetus.Embryogenesis starts with the fertilization of the ovum by sperm. The fertilized ovum is referred to as a zygote...
, playing a part in regulating activities such as cell division, migration, and differentiation.
Getting Help
Standard treatment of hypochondroplasia usually takes the form of orthopedic surgeryOrthopedic surgery
Orthopedic surgery or orthopedics is the branch of surgery concerned with conditions involving the musculoskeletal system...
and physical therapy
Physical therapy
Physical therapy , often abbreviated PT, is a health care profession. Physical therapy is concerned with identifying and maximizing quality of life and movement potential within the spheres of promotion, prevention, diagnosis, treatment/intervention,and rehabilitation...
. Genetic counseling
Genetic counseling
Genetic counseling or traveling is the process by which patients or relatives, at risk of an inherited disorder, are advised of the consequences and nature of the disorder, the probability of developing or transmitting it, and the options open to them in management and family planning...
is advised for patients and their families.
Etiology
This disorder is transmitted as an autosomal dominant trait affecting the FGFR3 gene on chromosomeChromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...
4p16.3.
There is no cure for this condition.