唐氏综合征/21-三体综合征Down Syndrome / 21-Trisomatic Syndrome转载2008-02-25

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什么是唐氏综合征?What is Downs syndrome? 唐氏综合征是Down综合征的音译又叫21-三体综合征、先天愚型,属常染色体畸变, 指挥舟舟就是这种病,这种先天白痴是社会和家庭的累赘,全人类的共识:最好消灭在胎儿期。所以现在产检中增加了专门的唐筛项目。 Dow

什么是唐氏综合征?What is Down's syndrome?

唐氏综合征是Down综合征的音译又叫21-三体综合征、先天愚型,属常染色体畸变, “指挥”舟舟就是这种病,这种先天白痴是社会和家庭的累赘,全人类的共识:最好消灭在胎儿期。所以现在产检中增加了专门的唐筛项目。

Down syndrome is a transliteration of Down syndrome, also known as 21-trisome syndrome, congenital fool type, is an autosomal aberration, "command" Zhouzhou is this disease, this congenital idiot is a burden on society and the family, the consensus of all mankind: It is best to eliminate in the fetal period. So now there is a special Tangshai project added to the birth test.

唐氏综合征的临床表现Clinical manifestations of Down's syndrome


The main features of Down's syndrome are low intelligence, slow physical development and special features. The children's eyes are wide, the nose beam is low, the eyes are small, the outside of the eyes is inclined, there is an internal skin, the outer ear is small, the hard palate is narrow, and the tongue often extends out of the mouth, and there is more salivation; Short stature, head circumference is less than normal, bone age often lags behind age, teeth delayed and often misplaced; Hair is soft and less; The limbs are short, because the ligaments are loose, the joints can be excessively bent, the fingers are short, and the small points are bent inwards. The characteristics of skin texture are: through hand, aid angle increase; The fourth and fifth fingers increase; The foot thumb ball is arched and the fifth finger has only one finger fold.


The child has a distinctive face at birth and it is difficult to feed. With the increasing of age, its low intelligence performance gradually became obvious, and the movement development and sexual development were delayed. About 30 % of children with congenital heart disease and other malformations. Due to low immune function, it is prone to various infections, and the incidence of leukemia has also increased by 10-30 times. If you survive to adulthood, you often develop Alzheimer's symptoms after the age of 30.

唐氏综合征的发病机制The pathogenesis of Down's syndrome


Down's syndrome is not a genetic disease. It is a product of genetic mutations. Older mothers are prone to occur. According to the karyotype analysis, children with 21-trisomatic syndrome can be divided into three types, of which the standard type and transposition type are not easy to distinguish clinically. The difference in clinical performance of the chimeric type is very large. Depending on the percentage of normal cell lines, it can be from near normal to typical phenotype.

(一)标准型 患儿体细胞染色体为47条,有一条额外的21号染色体,核型为47。XX(或XY),+21,此型占全部病例的95%。其发生机制系因亲代(多数为母方)的生殖细胞染色体在减数分裂时不分离所致。双亲外周血淋巴细胞核型都正常。

(I) There are 47 somatic chromosomes in standard children, with an additional chromosome 21 and a nuclear type of 47. XX(or XY), +21, this type accounts for 95 % of all cases. The mechanism of its occurrence is due to the non-separation of germ cell chromosomes in parent(mostly parent) during meiosis. Both parents have normal peripheral blood lymphocyte karyotypes.

(二)易位型 约占2.5%~5%。多为罗伯逊易位(Robertsonian translocation),是只发生在近端着丝粒染色体的一种相互易位,亦称着丝粒融合,其额外的21号染色体长臂易位到另一近端着丝粒染色体上。其中,D/G易位最常见,D组中以14号染色体为主,即核型为 46,XX(或 XY)-14,+t(14q21q);少数为15号。这种易位型患儿约半数为遗传性,即亲代中有 14/21平衡易位染色体携带者,核型为 45,XX(或 XY),-14,-21,+t(14q21q)。另一种为G/G易位,是由于G组中两个21号染色体发生着丝粒融合,形成等臂染色体t(21q21q),或一个21号易位到一个22号染色体上,t(21q22q),较少见。

(b) Diversion accounts for about 2.5 % to 5 %. Most of them are Robertson translocation, which is a kind of mutual translocation that occurs only at the proximal centromere chromosomes. It is also called centromere Fusion, and its extra long arm of chromosome 21 is translocated to another proximal centromere chromosome.. Among them, D/G transposition is the most common, and chromosome 14 is the main one in Group D, that is, the karyotype is 46, XX(or XY) -14, and + T(14q21 Q); A few are No. 15. About half of these translocation children are hereditary, that is, there are 14/21 balanced translocation chromosome carriers in the parent generation, and the nuclear type is 45, XX(or XY), -14, -21, and + T(14q21q). The other is the G/G translocation, which is due to the fusion of centromeres in the two chromosomes 21 in the G group.The arm chromosome T(21q21q), or a 21 translocation to a chromosome 22, T(21q22q), is rare.

(三)嵌合体型 约占本征的2%~4% 患儿体内有两种以上细胞株(以两种为多见),一株正常,另一株为21-三体细胞,本型是因受精卵在早期分裂过程中染色体不分离所引起,临床表现随正常细胞所占百分比而定。

(c) There are more than two cell lines(more common in two) in children with chimeric types of about 2 % to 4 % of the symptoms, one normal and the other 21-trisome cells. This type is caused by the non-separation of chromosomes during the early division of fertilized eggs, and clinical manifestations are determined by the percentage of normal cells.

唐氏综合征遗传咨询Genetic consultation on Down's syndrome


The recurrence risk rate of standard 21-trisomatic syndrome is 1 %, and the older the mother, the higher the risk rate. Parents of children with translocation should perform a nuclear analysis to find a balanced translocation carrier: if the parent is D/G translocation, there is a 10 % risk rate for each child; If parent D/G transposition, the risk rate is 4 %; The vast majority of G/G transposition cases are disseminated. Most of the parents 'nuclear types are normal, but there are also 21/21 transposition carriers, and the next generation is 100 % affected.


Treatment of Down Syndrome


There is no effective treatment.


The propituitary hormone therapy has a certain effect, and the application of female androgen can promote the development of sexual characteristics. But not fertile.


Prevention of Down Syndrome


Beijing Antai Hospital for Tangshai's high-risk people, using fetal mirror to remove umbilical cord blood for chromosome analysis can be quickly diagnosed, and induced labor.

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