Trisomy 18 and Trisomy 21 are both genetic diseases. Both are caused by an extra chromosome, which generally results in developmental delay, abnormally delayed growth rate, and intellectual disability.

The difference is:

1. The extra chromosome numbers are different

Trisomy 18 is an extra chromosome of chromosome 18.

Trisomy 21 is an extra chromosome on chromosome 21.

2. The names of the diseases are different

Trisomy 18 is also called Edwards syndrome.

Trisomy 21 is a form of congenital stupidity or tongue-sticking dementia.

3. Differences in appearance characteristics

Trisomy 18: protruding posterior head, small cranial deformity, droopy and deformed ears, abnormal micrognathia, small oral cavity, Hare lip, cleft palate, nose tip upward, wrinkles (cracks) in the eyelids, wide space between the eyes, drooping of the upper eyelids, overlapping and twisted fingers, underdeveloped thumbs (or complete disappearance), underdeveloped nails, in the first A webbing appears between the second and third toes, and the foot bends inward.

Trisomy 21: round face and flat head, small eye fissures, upward sloping eyes, exophthalmos, epicanthic folds, flat nose bridge, widely spaced eyes, small mouth, extended tongue, and both auricles Folded upper edge. Short stature, loose ligaments in the joints of the limbs, and the joints can bend excessively.

The face is round, the head is flat (see picture), the eye fissures are small, the outside is upward, the eyes are protruding, the epicanthic folds are flat, the bridge of the nose is flat, the distance between the eyes is wide, the mouth is small, the tongue is extended, and the upper edges of both auricles are fold. Short stature, loose joint ligaments in the limbs, and the joints can bend excessively. About one-third of the children have congenital heart disease and other deformities. Due to low immune function, they are susceptible to infectious diseases, and the incidence of leukemia is 10-10% higher than that of normal children. 30 times.

Extended information:

Human cells have 23 pairs of chromosomes (22 pairs of autosomes and one pair of sex chromosomes), that is, each cell has 46 chromatids.

Chromosomal translocations or chromosomal inversions do not cause disease in carriers, but they may increase the chance of the disease in their offspring.

Abnormal numbers of chromosomes or sets of chromosomes, also known as aneuploidy, can be fatal or may lead to genetic disorders.

Baidu Encyclopedia-Trisomy 21

Baidu Encyclopedia-Trisomy 18