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Pseudoachondroplasia is a type of short-limb dwarfism. It is a genetic autosomal dominant disorder. It is generally not discovered until 2-3 years of age, since growth is normal at first. Pseudoachondroplasia is usually first detected by a delay in crawling, walking, or a curious, waddling gait. Pseudoachondroplasia (also known as PSACH, Pseudoachondroplastic dysplasia, and Pseudoachondroplastic spondyloepiphyseal dysplasia syndrome) is an osteochondrodysplasia that results in mild to severely short stature due to the inhibition of skeletal growth primarily in the limbs (COMP 2008). Though similarities in nomenclature may cause confusion, Pseudoachondroplasia should not be confused with achondroplasia, which is a clinically and genetically distinct skeletal dysplasia (Francomano 2008). The allele involved in this disorder has been identified as (COMP) and is inherited as an autosomal dominant (OMIM 2008). ==Phenotype== This disorder is characterized by a notably short stature. The average height of adult males with the condition is around 120 centimeters (3 ft, 11 in), while adult females are typically around 116 cm (3ft, 9in). Affected individuals are not noticeably short at birth, though by two years of age their growth rate typically falls below the standard growth curve. Those affected by this disorder have normal facial features, head size and intelligence (Briggs et al. 1995). Other characteristic features of pseudoachondroplasia include short limbs, a waddling gait, early-onset joint pain caused by osteoarthritis, and a limited range of motion at the elbows and hips. Affected individuals also display short fingers and loose joints with loose ligaments and deformity of the legs (such as bowing). Radiography of the skeletons of patients with the disorder reveal abnormal growth and development of long bones, delayed bone formation in both the long bones and the vertebral column, which results in deformation of the vertebrae. Some individuals may even develop abnormal curvatures of the spine (scoliosis or lordosis) during childhood (Briggs et al. 1995). ==Inheritance== Pseudoachondroplasia is inherited in an autosomal dominant manner, though one case of a very rare autosomal recessive form has been documented. The offspring of affected individuals are at 50% risk of inheriting the mutant allele. Prenatal testing by molecular genetic examination is available if the disease-causing mutation has been identified in an affected family member (Hecht et al. 1995). 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「Pseudoachondroplasia」の詳細全文を読む スポンサード リンク
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