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Chapters
0:00 Introduction
0:53 Causes of Achondroplasia
2:54 Symptoms of Achondroplasia
3:47 Diagnosis of Achondroplasia
4:34 Treatment of Achondroplasia
Achondroplasia is a genetic disorder whose primary feature is dwarfism.[3] In those with the condition, the arms and legs are short, while the torso is typically of normal length.[3] Those affected have an average adult height of 131 centimetres (4 ft 4 in) for males and 123 centimetres (4 ft) for females.[3] Other features include an enlarged head and prominent forehead.[3] Complications can include sleep apnea or recurrent ear infections.[3] The disorder does not generally affect intelligence.[3]
Achondroplasia is caused by a mutation in the fibroblast growth factor receptor 3 (FGFR3) gene that results in its protein being overactive.[3] The disorder has an autosomal dominant mode of inheritance, meaning only one mutated copy of the gene is required for the condition to occur.[6] About 80% of cases result from a new mutation, which originates in the father's sperm.[5] The rest are inherited from a parent with the condition.[3] The risk of a new mutation increases with the age of the father.[4] In families with two affected parents, children who inherit both affected genes typically die before birth or in early infancy from breathing difficulties.[3] The condition is generally diagnosed based on the symptoms but may be confirmed by genetic testing.[5]
Treatments may include support groups and growth hormone therapy.[5] Efforts to treat or prevent complications such as obesity, hydrocephalus, obstructive sleep apnea, middle ear infections or spinal stenosis may be required.[5] Life expectancy of those affected is about 10 years less than average.[5] Achondroplasia is the most common cause of dwarfism[4] and affects about 1 in 27,500 people.[3]