Achondroplasia
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What is achondroplasia?Achondroplasia is a disorder of bone growth. Although achondroplasia literally means without cartilage formation, the problem is not in forming cartilage but in converting it to bone, particularly in the long bones of the arms and legs. All people with achondroplasia have short stature. The average height of an adult male with achondroplasia is 131 centimeters (4 feet, 4 inches), and the average height for adult females is 124 centimeters (4 feet, 1 inch). Characteristic features of achondroplasia include an average-size trunk, short arms and legs with particularly short upper arms and thighs, limited range of motion at the elbows, and an enlarged head (macrocephaly) with a prominent forehead. Fingers are typically short and the ring finger and middle finger may diverge, giving the hand a three-pronged (trident) appearance. People with achondroplasia are generally of normal intelligence. Health problems commonly associated with achondroplasia include episodes in which breathing slows or stops for short periods (apnea), obesity, and recurrent ear infections. In adulthood, individuals with the condition usually develop a pronounced and permanent sway of the lower back (lordosis) and bowed legs. Older individuals often have back pain, which can cause difficulty with walking. How common is achondroplasia?Achondroplasia is the most common type of short-limbed dwarfism. The condition occurs in 1 in 15,000 to 40,000 newborns. What genes are related to achondroplasia?Mutations in the FGFR3 gene cause achondroplasia. The FGFR3 gene provides instructions for making a protein that is involved in the development and maintenance of bone and brain tissue. This protein limits the formation of bone from cartilage (a process called ossification), particularly in the long bones. Two specific mutations in the FGFR3 gene are responsible for almost all cases of achondroplasia. Researchers believe that these mutations cause the protein to be overly active, which interferes with skeletal development and leads to the disturbances in bone growth seen with this disorder. How do people inherit achondroplasia?Achondroplasia is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. About 80 percent of people with achondroplasia have average-size parents; these cases result from a new mutation in the FGFR3 gene. In the remaining cases, people with achondroplasia have inherited an altered FGFR3 gene from one or two affected parents. Individuals who inherit two altered copies of this gene typically have very severe problems with bone growth, and are usually stillborn or die shortly after birth from respiratory failure.
Source: National Institutes of Health
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Research reports on achondroplasia in children from Hospital for Special Surgery provide new insights
2007 FEB 27 -- Researchers detail in "Advances in understanding etiology of achondroplasia and review of management," new data in achondroplasia. According to a study from the United States, "A summary of management and current research in achondroplasia (OMIM 100800). The most common nonlethal skeletal dysplasia, achondroplasia presents a distinct clinical picture evident at birth." "Substantial information is available concerning the natural history of this dwarfing disorder. Diagnosis is made by clinical findings and radiographic features. Characteristic features include short limbs, a relatively large head with frontal bossing and midface hypoplasia, trident hands, muscular hypotonia, and thoracolumbar kyphosis. Children commonly have recurrent ear infections, delayed motor milestones, and eventually develop bowed legs and lumbar lordosis. People with achondroplasia are generally of normal intelligence. The genetic cause of achondroplasia was discovered in 1994. Subsequent research efforts are designed to better characterize the underlying possible biochemical mechanisms responsible for the clinical findings of achondroplasia as well as to develop possible new therapies and/or improve intervention. Establishing a diagnosis of achondroplasia allows families and clinicians to provide anticipatory care for affected children," wrote E.M. Carter and colleagues, Hospital for Special Surgery. The researchers concluded: "Although the primary features of achondroplasia affect the skeleton, a multidisciplinary approach to care for children with achondroplasia helps families and clinicians understand the clinical findings and the natural history of achondroplasia in order to improve the outcome for each patient." Carter and colleagues published the results of their research in Current Opinion In Pediatrics (Advances in understanding etiology of achondroplasia and review of management. Current Opinion In Pediatrics, 2007;19(1):32-7). For additional information, contact E.M. Carter, Hospital for Special Surgery, The Center for Skeletal Dysplasias, New York 10021 USA. The publisher of the journal Current Opinion In Pediatrics can be contacted at: Lippincott Williams & Wilkins, 530 Walnut St., Philadelphia, PA 19106-3621, USA. Keywords: United States, Achondroplasia, Genetics, Orthopedics. This article was prepared by Science Letter editors from staff and other reports. Copyright 2007, Science Letter via NewsRx.com.
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