Notes Achondroplasia is a bone growth disorder that causes disproportionate dwarfism. Dwarfism is defined as a condition of short stature as an adult. People with achondroplasia are short in stature with a normal sized torso and short limbs. It is the most common type of disproportionate dwarfism. Achondroplasia is a disorder of bone growth. It is the most common form of disproportionate short stature. It occurs in one in every 15,000 to one in 40,000 live births. Achondroplasia is caused by a gene alteration (mutation) in the FGFR3 gene. The FGFR3 gene makes a protein called fibroblast growth factor receptor 3 that is involved in converting cartilage to bone. FGFR3 is the only gene known to be associated with achondroplasia. All people who have only a single copy of the normal FGFR3 gene and a single copy of the FGFR3 gene mutation have achondroplasia.
Most people who have achondroplasia have average-size parents. In this situation, the FGFR3 gene mutation occurs in one parent's egg or sperm cell before conception. Other people with achondroplasia inherit the condition from a parent w Is achondroplasia inherited?
Most cases of achondroplasia are not inherited. When achondroplasia is inherited, it is inherited in an autosomal dominant manner.
Over 80 percent of individuals who have achondroplasia have parents with normal stature and are born with achondroplasia as a result of a new (de novo) gene alteration (mutation). These parents have a small chance of having another child with achondroplasia.
A person who has achondroplasia who is planning to have children with a partner who does not have achondroplasia has a 50 percent chance, with each pregnancy, of having a child with achondroplasia. When both parents have achondroplasia, the chance for them, together, to have a child with normal stature is 25 percent. Their chance of having a child with achondroplasia is 50 percent. Their chance for having a child who inherits the gene mutation from both parents (called homozygous achondroplasia - a condition that leads to death) is 25 percent.
Top of pageho has achondroplasia. Down syndrome (DS) or Down's syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy ofchromosome 21.[1] Down syndrome is the most common chromosome abnormality in humans.[2] The CDC estimates that about one of every 691 babies born in the United States each year is born with Down syndrome.[3] It is typically associated with physical growth delays, a particular set of facial characteristics and a severe degree of intellectual disability.[1] The average full-scale IQ of young adults with Down syndrome is around 50 (70 and below is defined as the cut-off for intellectual disability), whereas young adult controls have an average IQ of 100.[1][4]
Many children with Down syndrome are educated in regular school classes while others require specialised educational facilities. Some children graduate from high school,[5] and, in the US, there are increasing opportunities for participating in post-secondary education.[6] Education and proper care has been shown to improve quality of life significantly.[7] Many adults with Down syndrome are able to work at paid employment in the community, while others require a more sheltered work environment.[5]
Down syndrome is named after John Langdon Down, the British physician who described the syndrome in 1866.[8] The condition was clinically described earlier by Jean-Étienne Dominique Esquirol in 1838 and Édouard Séguin in 1844.[9] Down syndrome was identified as a chromosome 21trisomy by Dr. Jérôme Lejeune in 1959. Down syndrome can be identified in a newborn by direct observation or in a fetus by prenatal screening.[1][10]Pregnancies with this diagnosis are often terminated.[11]
Contents
[hide] * 1 Signs and symptoms * 1.1 Neurological effects * 1.2 Congenital heart disease * 1.3 Cancer * 1.4 Thyroid disorders * 1.5 Gastrointestinal * 1.6 Infertility * 1.7 Eye disorders * 1.8 Hearing disorders * 1.9 Other complications * 2 Genetics * 2.1 Trisomy 21 * 2.2 Robertsonian translocation * 3 Diagnosis * 3.1 Prenatal testing * 3.1.1 Ultrasound * 3.1.2 Blood tests * 3.1.3 Amniocentesis and CVS * 3.1.4 Abortion rates * 3.2 Postnatal diagnosis * 4 Management * 4.1 Plastic surgery * 4.2 Cognitive development * 5 Epidemiology * 6 History * 7 Society and culture * 7.1 Ethical issues * 7.2 World Down Syndrome Day * 7.3 Notable individuals * 8 Footnotes * 9 References * 10 External links
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