Achondroplasia

Achondroplasia is the most common cause of short stature or dwarfism. People with achondroplasia have disproportionate bodies with short arms and legs, and other classic physical signs such as curvature of the spine. The abnormal bone growth can cause constriction of soft tissues, creating a variety of health problems. Achondroplasia is an inherited genetic condition. Recently a prenatal test has been developed to detect achondroplasia in uterus; a study is under way to assess the implications of this testing.

• Typical appearance of achondroplastic dwarfism is apparent at birth
• Short stature
• Short limbs, proximal extremity (upper arm and thigh)
• Large-appearing head
• May be associated with clubfoot
• Skeletal (limb) abnormalities
• Abnormal hand appearance (trident hand) 
  
  Note: A family history of achondroplasia should alert parents to the possibility of having an affected child. Typical appearance of achondroplastic dwarfism is apparent at birth.
  
  

Achondroplasia is a genetic disorder of bone growth that is evident at birth. It affects about one in every 20,000 births and it occurs in all races and in both sexes. Its depiction in ancient Egyptian art makes it one of the oldest recorded birth defects. The word achondroplasia is derived from Greek and means "without cartilage formation," although individuals with achondroplasia do have cartilage. During fetal development and childhood, cartilage normally develops into bone, except in a few places, such as the nose and the ears. In individuals with achondroplasia, something goes wrong during this process, especially in the long bones (such as those of the upper arms and thighs). The rate at which cartilage cells in the growth plates of the long bones turn into bone is slow, leading to short bones and reduced height.

Achondroplasia is caused by an abnormal gene located in one of the chromosomes (humans have 23 pairs of chromosomes). In some cases, a child inherits achondroplasia from a parent who also has the condition. If one parent has the condition and the other does not, the chances of deformity lessens with each pregnancy by 50%. If both parents have achondroplasia, there is a 50 percent chance that the child will inherit the condition, a 25 percent chance that the child will not have it, and a 25 percent chance that the child will inherit one abnormal gene from each parent and have severe skeletal abnormalities that lead to early death. A child who does not inherit the gene will be completely free of the condition, and cannot pass it on to his or her own children. In most cases (over 80 percent), however, achondroplasia is not inherited but results from a new mutation (change) that occurred in the egg or sperm cell that formed the embryo. The parents of children with achondroplasia, resulting from new mutations, are usually average-sized.

Examination of the infant shows increased front-to-back head size (occipital-frontal circumference). There may be signs of hydrocephalus associated with enlargement of the chambers within the center of the brain (ventricular dilatation).

Use foods that are rich in calcium for the proper development of bones. Taking milk helps and also following a diet that is rich can be useful.

Encourage the child to participate in activities that aren’t too stressing for him; however avoid gymnastics, high diving, acrobatics, and collision sports. Encourage the child to socialize in an age-appropriate way, and work with the teacher and the other children so that the child is not given unnecessary special privileges. Assist in adapting to an independent life.