propeptidase deficiency
Introduction
Introduction to peptidase deficiency Prolidasedeficiency is an autosomal recessive disorder that often affects the central nervous system of the skin, eyes, ears, nose, pharynx, and joints. Laboratory tests for prolidase activity Deletion and imino dipeptide urine are characteristic, first reported by Goodman et al in 1968. basic knowledge The proportion of illness: 0.0021% Susceptible people: good for children Mode of infection: non-infectious Complications: Osteoporosis
Cause
Cause of peptidase deficiency
(1) Causes of the disease
Prolidase deficiency is an autosomal recessive disorder.
(two) pathogenesis
Under normal conditions, collagen is degraded to iminodipeptide and other kinds of dipeptides, and the aminoamino group and the -carboxyl-terminal imino dipeptide are respectively in the aminoacyl proline (dipeptide) and prolyl amino acids. The proline is decomposed by the action of the (dipeptide) enzyme, which can be reused when the collagen is synthesized. When the aminoacyl proline (dipeptide) enzyme is deficient, the imino group terminated by the amino group The peptide cannot be decomposed into proline, and the recyclable proline is significantly reduced in collagen synthesis, and collagen synthesis is insufficient, resulting in various clinical manifestations.
Prevention
Peptidase deficiency prevention
Marriage guidance and birth guidance for patients with genetic diseases and their relatives, if necessary, ligation surgery or termination of pregnancy, can prevent the birth of children, reduce the corresponding disease-causing genes in the population. Marriage guides autosomal dominant genetic diseases can cause death, disability, and fools. The risk of illness in the next generation is 50%. It is obvious that marriage is not suitable. Marriage between heterozygous recessive genetic diseases is the most important source of children with severe genetic diseases, so it is necessary to discourage marriage between two heterozygotes. In the case of unconditional heterozygous detection, close relatives should be avoided as much as possible, because the frequency of a disease-causing gene in relatives is much higher than that of the general population, so the chances of genetically heterozygous for both close relatives are greatly increased. For example, the frequency of heterozygotes in the phenylketonuria group is 1:/50, and the probability of non-close relatives being born with homozygous children is 1/50×1/50×1/4=1 /10000, such as cousin marriage. The probability of birth is 1/50×1/8×1/4=1/600, and the difference between non-close relatives is about 6 times. The lower the incidence rate, the higher the incidence of recessive genetic disease, the proportion of children born to close relatives, and the higher the rate of marriage than non-close relatives. According to the World Health Organization, the infant mortality rate for non-close relatives is 24, while that for close relatives is 81, which is about 3 times higher. Therefore, Article 6 of Chapter 2 of the Marriage Law of the People's Republic of China stipulates that "the relatives of blood and the relatives within the third generation cannot marry", which is in line with the principle of eugenics.
Complication
Peptidase deficiency complications Complications Osteoporosis
There may be visual impairment, nasal septal defect, and mental retardation.
Symptom
Peptidase deficiency symptoms common symptoms saddle-nose visual impairment mental retardation osteoporosis rash
85% of patients have skin lesions, mostly before the age of 12, mainly manifested as maculopapular rash, chronic intractable ulcer, purpura, thinning of the skin, anthropoid palmprint and keratosis, mainly distributed in the face, limbs and back Back, in addition, the patient may have saddle nose, hypertelorism, thick lips, missing teeth and jaw dysplasia and other special faces, osteoporosis, knee ligament relaxation, joint overstretching, femoral external rotation Duck steps, other visual impairment, nasal septal defect, mental retardation.
Examine
Examination of purine peptidase deficiency
The urine contains a large amount of iminodipeptide, the activity of the amino acid proline (dipeptide) enzyme on the surface of the red blood cells and the leukocyte is absent, and the activity of the enzyme on the fibroblasts is decreased. In addition, low hemoglobin anemia and thrombocytopenia are also reported. Myeloproliferative, anti-streptolysin "O" and gamma-globulin increased.
Histopathology: no abnormalities were found in the epidermis around the skin ulcer. In the dermis, stained with Congo red, and amorphous material was observed around the capillaries. Electron microscopy showed that this was amyloid, collagen fibers were broken, arranged disorderly or in blocks. Shape, but no abnormalities in the structure of collagen fibers were observed under electron microscope.
Diagnosis
Diagnosis and identification of purine peptidase deficiency
The disease has various symptoms and signs in the skin, blood vessels, bones and joints, and the nervous system. For example, if an imino dipeptide is found in the urine, the diagnosis can be established.
