chromosome

Chromosome is an object with genetic properties in the cell. It is easily dyed dark by basic dyes, so it is called chromosome (chromatin). Chromosome is a substance containing genetic information (gene) in the nucleus and is a cylinder under the microscope. It is composed of deoxyribonucleic acid and protein, and is easily colored by basic dyes (such as gentian violet and acetate magenta) during the mitotic stage of cells, hence the name. Basic Information Specialist classification: growth and development check classification: genetic testing (DNA) Applicable gender: whether men and women apply fasting: fasting Included items: X chromatin Tips: No special precautions. Normal value Male 46, XY; female 46, XX. Clinical significance 1. Sex chromosome number and morphology abnormalities: (1) The X chromosome is missing Turner syndrome 45, with 45 X chromosomes and only one X chromosome. The phenotype is female, but the gonadal dysplasia, secondary sexual development delay or hypoplasia. Short, low ear, high squat, small jaw, posterior hairline, short neck, neck, shield chest, wide breast, elbow valgus and mental retardation may be mild. There are still karyotypes of 45, X/46, XX chimera; X chromosome long arm deletion; X chromosome short arm deletion; X chromosome long and short arm deletion; circular X chromosome; X chromosome long arm equipotential chromosome and X Chromosomes and autosomal translocations may also have different manifestations of Turner's syndrome. (2) Excessive X chromosome 47, XXX48, XXXX49, XXXXX and their chimeras with normal chromosomes. Most of the phenotypes are female, some have hypogonadal hypoplasia, and there are no obvious abnormalities and fertility. (3) Y chromosome excess and abnormal Klinfelter syndrome; 47, XXY patients are male, mostly tall, with small and hard testicles, lack of sperm, more breast development, female body type, The body hair is small, the arms and legs are long and the intelligence may be dull. 47,XYY karyotype is rare, the patient is male, most of them are tall, are searched, have poor intelligence, may have mental illness and illegal behavior, and quite a few people have no clinical abnormalities. (4) Patients with both sexes and true hermaphroditis have both testis and ovarian tissue. Its posture, secondary sexual characteristics and external genitalia are like women and men. Most of its karyotypes are 46, XX, and a few can be 46, XY or 46, XX/46, XY, 45, X/46, XY, etc. chimeras. Patients with testicular feminization syndrome have normal appearance but have XY chromosome and testicular tissue. In patients with XY gonadal dysgenesis, their gonads and secondary signs are often as hypoplastic as Turner's syndrome. 2, the number of autosomes and abnormal morphology DOWwn syndrome (congenital type) typical trisomy 21, there are 47 chromosomes, one more chromosome 21, is the most common type of autosomal abnormality. The incidence of babies born to older mothers is higher. The patient has obvious dementia and appearance, palm, skin and other special features, the child is susceptible to infection and prone to leukemia, and most of them are difficult to live to adulthood. 21 and 21, 21 and 22, 21 and 14 and other Robertsonian translocation and 21 trisomy and normal nuclear chimerism can have a congenital stupid performance. The task of eugenics is to improve the quality of the population. Prenatal diagnosis, genetic counseling, and early detection of hereditary diseases such as trisomy 21 are of great significance. Edwad syndrome is a trisomy 18 syndrome. The child has 47 chromosomes and one more chromosome 18. The incidence rate in newborns is about 1/4,500, and most of them die during childbirth or after childbirth. There are many kinds of deformities. Patar syndrome is a trisomy 13 with 47 chromosomes and 1 chromosome in group D. The incidence rate is about 4/100,000. There are many malformations. It is more common in abortion, premature infants or soon after birth. Newborn. In addition, in the newborn or abortion, there are occasional trisomy 8, trisomy, trisomy 22 and trisomy (ie, there are two trisomy in the same individual, for example, there are 21 trisomy and There are X three bodies). The remaining three pairs are very rare and are often seen only in spontaneous abortions. Autosomal deletions are mostly lethal and rarely survive. Occasionally, reports of 21 monomers, 13 monomers and 22 monomers. 3, the main types of autosomal structural abnormalities are part of the arm missing: partial arm repetition and a variety of translocations. (1) 5P-syndrosis is also called "cat called syndrome" because of the child crying like a cat, and the short arm part is missing on the chromosome 5. There are a variety of deformities such as small head, wide eye distance, downward tilting of the eye, low ear, and through hands. About half of the patients have congenital heart disease, low intelligence, poor living ability, and often die early. (2) 4P-syndrome is similar to 5P-syndromes, but it is often more aggravated. It can also be hypospadias, cleft palate, severe mental and motor disorders, seizures, etc., which are rare cases. (3) 18P-syndrome occasionally survived. (4) A large number of chromosome breaks can be seen in chromosome break syndrome, mostly due to Fanconi syndrome and Bloom syndrome. (5) Fragile X syndrome In the pathological situation, some chromosome breaks occur frequently, called fragile chromosomes. This disease is one of them. After culturing in a medium without (low) folic acid, breaks or cracks are likely to occur at the Xq27-28 site. The patient is more common in men, with mental retardation, loneliness, long face, big ears, large testicles, large genitalia, and jaw protrusion; in women, the symptoms are mild, and about 1/3 are mild mental retardation. (6) The Philadelphia chromosome (Ph') was named for its first appearance in Philadelphia, USA. It is a translocation of the long arm of chromosome 22 to the long arm of chromosome 9. A special chromosomal abnormality that is seen in chronic myeloid leukemia, but is even seen in a few other acute leukemias. This is also the only chromosomal variation in malignant cell chromosomal variation that has been recognized to have a constant change. It is necessary for both couples with infertility and habitual abortion to check chromosomes or perform prenatal amniocentesis analysis. Since radiation can cause chromosomal damage, it is necessary to monitor the chromosomes of people exposed to or exposed to radiation. Certain substances can obviously cause chromosomal abnormalities called "mutagenic agents", which must be analyzed by teratogenic tests, sister chromatid exchange and other chromosomes. Chromosome analysis is also widely used in the research of viruses and tumor diagnosis. Positive results may be diseases: chromosomal abnormalities, dwarfism, genetic diseases, congenital testicular hypoplasia in children, hematoporphyrin peripheral neuropathy, mental retardation, pediatric autosomal dominant cerebellar ataxia, familial hemorrhagic nephritis, pediatric Sexual malformation, pediatric Down syndrome considerations Generally, it is directly to the hospital for examination, and there is no special attention. Inspection process Peripheral blood culture method, peripheral blood leukocyte culture using a dry sterilization syringe to draw venous blood ml, into a sterile anti-coagulation tube for 2 hours, after taking the white cell suspension into the culture medium for 72 hours, add colchicine, centrifuge The supernatant is on a slide. Fixed staining was observed under oil. Not suitable for the crowd There are no special taboos. Adverse reactions and risks This test generally does not cause complications and harm.

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