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Prolidase deficiency (PD) is an autosomal recessive disease that is extremely uncommon and is associated with collagen metabolism and affects the connective tissues. This rare condition affects assorted systems because of an error on an enzyme, which is affiliated with the creation of collagen. Collagen is a powerful protein that is observed in the bones, tissues, and the skin. Collagen causes the degradation of iminodipeptides. Iminodipeptides are compounds, which break down to form amino acids. Prolidase is an enzyme responsible for the breaking down of iminodipeptides. In this condition there is a defect, which causes a lack of prolidase. Those affected by PD eliminate large quantities of iminodipeptides in their urine because of a deficiency in the prolidase enzyme. When the function of prolidase operates incorrectly it results in this recessive connective tissue condition (PD). Prolidase splits dipeptides that contain C-terminal proline or hydroxyproline. When the amount of prolidase is insufficient, the typical recycling of the residues of proline, acquired from the degrading of collagen, is not functioning properly. As a result, there is an accumulation of iminodipeptides causes disruptions in the connective tissue metabolism and elimination of an excessive volume of iminodipeptides in the urine. It is estimated that about 70 people with this condition have been recorded in medical literature. Those who have researched this disorder predict that this condition exists in about 1 in 1 million to 1 in 2 million newborns/infants.〔(【引用サイトリンク】url=http://ghr.nlm.nih.gov/condition=prolidase-deficiency )〕 The characteristics of this disorder are extremely inconsistent in their expression. ==Characteristics and Symptoms== Prolidase deficiency generally becomes evident throughout infancy, but the initial symptoms can appear from the time of birth to young adulthood. This condition results in very diverse symptoms.〔 The seriousness of the symptoms exhibited in PD can be significantly inconsistent between those who are affected. It is possible for individuals who are affected by this condition to be asymptomatic. In those people who exhibit no symptoms, this disorder can be identified through laboratory testing. For instance, newborn screening testing or testing extended to the family members of those who are influenced by this condition. One of the primary features of prolidase deficiency is the passing of high quantities of proteins (peptides) through urine. In addition, most of those affected exhibit skin lesions or ulcers on the skin that are persistent. The majority of these ulcers are seen on the legs and feet. The severity of these skin lesions normally begins during childhood, and may span from a mild rash to skin ulcers that are more severe.〔 The skin ulcers particularly on the legs could possibly not entirely heal, which can cause difficulties that could lead to infection and amputation. Those affected by PD can also suffer from intellectual disabilities that can range from mild to more serious. The development of children who are affected could progress more slowly and approximately 75% of those who have PD have an intellectual disability. These individuals also have an elevated vulnerability to infections, particularly the infections of the respiratory system. Some who suffer from PD acquire recurrent lung disease. Clinically, the distinguishing feature that is seen most frequently, and exists in the majority of those affected is the appearance of dermatological problems. The abundant amounts of those who suffer from this condition exhibit abnormal facial characteristics. The distinguishing facial appearance in those who have PD consist of, pronounced eyes which are spaced far apart (hypertelorism), a high forehead, a compressed bridge of the nose or saddle nose, and a small lower jaw and chin (micrognathia).〔 In addition to the symptoms stated, those with prolidase deficiency are also vulnerable to serious skin or ear infections and possibly respiratory tract infections that could risk their lives. Affected individuals may also have an enlarged spleen (splenomegaly), and on some occasions the spleen and liver may both be enlarged (hepatosplenomegaly).〔 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「prolidase deficiency」の詳細全文を読む スポンサード リンク
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