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a group of hereditary disorders in which bone or cartilage grows abnormally,
so that the skeleton develops abnormally. Many types of osteochondrodysplasia
cause dwarfism. Achondroplasia is the most
common of the many types of short-limbed dwarfism.
Symptoms and Signs
Individuals with achondroplasia have short stature caused
by rhizomelic shortening of the limbs, characteristic faces with frontal
bossing and mid-face hypoplasia, exaggerated lumbar lordosis, limitation
of elbow extension and rotation, bow legs ,
and trident appearance of the hands. Hyperextensibility of the knees and
most other joints is common. Intelligence is usually normal. Average adult
height for men with achondroplasia is 131 5.6 cm; for women, 124 5.9 cm.
Obesity is a major problem in achondroplasia.
In infancy, mild to moderate hypotonia is usual, and acquisition of developmental motor milestones is often delayed. Infants have difficulty in supporting their heads due to both hypotonia and large head size. True megalencephaly occurs in individuals with achondroplasia, but intelligence is normal unless hydrocephalus or other central nervous system complications occur. The large head of the newborn with achondroplasia creates an increased risk of intracranial bleeding during vaginal delivery . Hydrocephalus may be caused by increased intracranial venous pressure due to stenosis of the sigmoid sinus at the level of the narrowed jugular foramina. Recurring otitis media is frequently a problem. As many as 7.5% of infants with achondroplasia die in the first year of life from obstructive apnea or central apnea.
Diagnosis and Treatment
Achondroplasia can be diagnosed by characteristic clinical and radiographic findings in most affected individuals. In individuals who may be too young to diagnose with certainty or in atypical cases, DNA-based testing can be used to detect a mutation in the FGFR3 gene (chromosomal locus 4p16). Such testing is 99% sensitive and is widely available. Molecular genetic testing can be helpful in the diagnosis of newborns and atypical cases and in prenatal testing.
Recommendations for management of children with achondroplasia were outlined by the American Academy of Pediatrics, Committee on Genetics. These recommendations of the committee are meant to supplement guidelines available for treating the child with average stature. The recommendations include, but are not limited to, the following measures:
Treatment of obstructive sleep apnea may
include adenotonsillectomy, weight reduction, continuous positive airway
pressure (CPAP) by nasal mask, and trachesostomy for extreme cases. Improvement
in disturbed sleep and some improvement in neurological function can result
from these interventions.
Genetic counselling may be of use to those with this disorder.
The information in this page is presented in summarised form and has been taken
from the following source(s):
|http://www.hon.ch/Dossier/MotherChild/child_musculoskeletal/muscoskel_osteochondrodysplasia.html||Last modified: Jun 25 2002|