Cartilage-hair hypoplasia (CHH) or McKusick type metaphyseal chondrodysplasia is a rare form of dwarfism. It is inherited in an autosomal recessive manner (see the genetics section for further details). This form of dwarfism was first described in the Old Order Amish in the United States. In the Amish, the incidence of CHH is 1.5 in 1,000births. CHH is also found in Finland at a high frequency, approximately1 in 23,000 births. CHH is characterized by short limb short stature, fine, sparse hair, impaired immunity, and anemia. At birth, weight is normal but length is decreased. Individuals with CHH have a long trunk in relation to short limbs. All segments of the limbs are shortened (i.e. the upper arm, forearm, and hands are shortened, in contrast to achondroplasia where only the upper parts of the limbs are shortened). Adult height ranges from 103cm to 149cm(median adult female height is 123 cm and median adult male height is 131cm).
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