Increased incidence of the ape line and increased atd angle

Introduction Due to the absence of chromosome segregation in the late stage of cell division or the occurrence of cleavage and reconnection under the influence of various factors in vivo and in vitro. The lack of a chromosome 14 adds a new chromosome, which is connected by a 21 and a 14 chromosome to form a new 14/21 chromosome. In the performance of urner syndrome, the two palms and the palm pleats merged into a single chance, and the atd angle increased, ie >63° (normal <45°). There is no effective treatment for this disease, mainly prevention.

Cause

When treating cells in culture with viruses, it often causes many types of chromosomal aberrations, including rupture, comminuted and interchangeable chromosomal abnormalities, which can often manifest as familial tendencies, suggesting that chromosomal aberrations are related to hereditary autoimmune diseases. It plays a role in chromosome segregation, such as the correlation between increased thyroid primary autoimmune antibodies and familial chromosomal abnormalities.

an examination

Related inspection

Amniocentesis check chromosome

Amniocentesis in pregnant women: chromosomal abnormalities in amniotic fluid cells can be found, and early diagnosis of children with Down syndrome and other chromosomal hypoplasia can be screened. Mothers are the majority of chimeras and fewer fathers. If the mother is a carrier, the offspring of the child are 100%. The karyotype is 46XX (or XY) 21, and this disease is 2%.

If there are more than 2 signs and 21 signs in a family, it may be related to their parents' chimera.

Chromosome examination: Fluorescence in situ hybridization (fluorescence in situ hybridization technique) can be used to detect amniocytes or chromosomes in patients. For example, Down syndrome can be found that chromosome 21 is triploid.

Differential diagnosis

1, 21 trisomy: the karyotype of the genome is 47XX (or XY) octa 21, accounting for 90 to 95%. The total number of chromosomes in the child is 47, due to the addition of a small end-pointing chromosome (belonging to the 21st pair). This phenomenon is called trisomy because there is a pair of chromosomes that become three. When the mother is older than 35 years old, the incidence is significantly increased (about 125 times the population incidence rate). The parents have no abnormal chromosomes and no family history, so it is considered that the mother's gametes (eggs) are not separated by chromosomes. About 1/5 cases were caused by the separation of the father's chromosomes. In the case of an ovarian twin, if one is trisomy 21, 100% of the other child is also a trisomy 21 syndrome. In the case of two-oval twins, the chances of the two children being the trisomy 21 are only 30%.

2. Translocation type: The total number of chromosomes in a few cases is 46. The chromosome 21 still has a trisomy character and is accompanied by distortion of other chromosomes. There are several different situations:

(1) D/G translocation: The lack of a chromosome 14 adds a new chromosome, which is connected by a 21 and a chromosome 14 to form a new 14/21 chromosome. This chromosome retains most of the genetic material of chromosomes 14 and 21, so in fact, the patient's cells still have three chromosomes 21 (trisomy), and the karyotype is 46XX (or XY) 21 . t(Dq21q). This type of child accounts for 2%, and the mother's appearance is normal, but the number of chromosomes in the cell is 45, one of which is 14/21 chromosome. The aunt and the cousin of the child may have the same disease.

(2) G/G translocation: translocation of chromosomes 121 and 22, forming a 21/22 chromosome, possibly inherited by the patient's father; 2 an isochon chromosome connected by two chromosomes 21, There is a normal chromosome 21, such as the mother is a carrier, and its offspring 100% of the children. The karyotype is 46XX (or XY) 21, and this disease is 2%.

(3) Chimera type: 1% to 2%, karyotype is 47XX (or XY) 21/46XX (or XY). Less common, the chromosomes in the cells of the sick children vary from 46 to 45 or 45. This type is mainly caused by errors in the fertilized egg during the cleavage stage. Some of the 21 triad patients had normal parental phenotypes, and had a 21 trisomy chimera, with the mother being the chimera and the father having fewer fathers. If there are more than 2 signs and 21 signs in a family, it may be related to their parents' chimera.

A chromosome check can be diagnosed.

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