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Achondroplasia is a common cause of dwarfism. It occurs as a sporadic mutation in approximately 80% of cases (associated with advanced paternal age) or it may be inherited as an autosomal dominant genetic disorder. People with achondroplasia have short stature, with an average adult height of for males and for females. Achondroplastic adults are known to be as short as . If both parents of a child have achondroplasia, and both parents pass on the mutant gene, then it is very unlikely that the homozygous child will live past a few months of its life. The prevalence is approximately 1 in 25,000. ==Signs and symptoms== * Disproportionate dwarfism * Shortening of the proximal limbs (called rhizomelic shortening) * Short fingers and toes with trident hands * Large head with prominent forehead frontal bossing * Small midface with a flattened nasal bridge * Spinal kyphosis (convex curvature) or lordosis (concave curvature) * ''Varus'' (bowleg) or ''valgus'' (knock knee) deformities * Frequently have ear infections (due to Eustachian tube blockages), sleep apnea (which can be central or obstructive), and ''hydrocephalus'' 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「achondroplasia」の詳細全文を読む スポンサード リンク
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