Achondroplasia
The most common form of short stature with disproportionately short limbs — dwarfism with short arms and legs. Achondroplasia is caused by mutation in the fibroblast growth factor receptor-3 gene (FGFR3), which is located on chromosome 4 in chromosome band 4p16.3.
Aside from short arms and legs, the fingers are short and the ring and middle fingers diverge giving the hand a trident (three- pronged) appearance. There is a typically large head with prominence of the forehead (frontal bossing), underdevelopment (hypoplasia) of the midface with cheekbones that lack prominence, and a low nasal bridge with narrow nasal passages. The brain is normal and intelligence is entirely normal in achondroplasia. However, the complications of achondroplasia can impinge on the brain and the spinal cord.
Achondroplasia is inherited as an autosomal dominant trait affecting boys and girls equally. The parents of children with achondroplasia are more often than not normal. Most cases of achondroplasia are due to new mutations that appear for the first time in the affected children.
Achondroplasia can be diagnosed before birth by molecular means. The limited number of changes in the FGF3 gene responsible for achondroplasia and the ease with which they can be detected provide the basis for a simple method for prenatal diagnosis.
Read Also:
- Achoo syndrome
Autosomal dominant: A pattern of inheritance in which an affected individual has one copy of a mutant gene and one normal gene on a pair of autosomal chromosomes. (In contrast, autosomal recessive diseases require that the individual have two copies of the mutant gene.) Individuals with autosomal dominant diseases have a 50-50 chance of passing […]
- Achromatopsia
Achromatopsia: A hereditary disorder of sight due to a lack of cone vision – that type of vision provided by the cone photoreceptors in the retina. In the normal eye, there are some 6 million cone photoreceptors; they are located largely in the center of the retina. Lacking cones, persons with achromatopsia have to rely […]
- Acid deposition
Acid deposition: A complex chemical and atmospheric phenomenon that occurs when emissions of sulfur and nitrogen compounds and other substances are transformed by chemical processes in the atmosphere and then deposited on earth in either wet or dry form. The wet forms, popularly called acid rain, can fall to earth as rain, snow, or fog. […]
- Acid indigestion
Heartburn.
- Acid phosphatase
Acid phosphatase: An enzyme that acts to liberate phosphate under acidic conditions and is made in the liver, spleen, bone marrow, and prostate gland. Abnormally high serum levels of acid phosphatase may indicate infection, injury, or cancer of the prostate.