Happy children refer to people with mental disorders. Han children belong to vulnerable groups. Compared with the physically disabled, the visually impaired and the hearing impaired, the mentally retarded are more difficult to adapt to the society, because they can't work and live normally due to various factors such as intelligence, and they can only rely on the care and love of others.

The official name of Xi Han's ear is Down syndrome, which is a chromosomal defect disease, also known as "congenital stupidity", and is one of the first mixed mental retardation syndromes. Down syndrome is caused by gene distortion. Children's chromosome 2 1 changes from normal chromosome 2 to chromosome 3, so it is also called "2 1 trisomy syndrome".

Extended data:

Children with Down syndrome have obvious special facial signs, such as wide eye distance, low nasal root, small eye fissure, oblique eye, epicanthus, small external ear, fat tongue, frequent spitting and drooling. Short stature, smaller head circumference than normal people, short head back and forth diameter, flat head pillow. The neck is short and the skin is slack. Bone age often lags behind age, delayed teething and frequent dislocation.

Hair is soft and less. The anterior fontanel closed late, and there may be a third fontanel in the occipital midline. The limbs are short, the joints can be excessively bent due to ligament relaxation, the fingers are thick and short, and the middle phalanx of the little finger is underdeveloped, which makes the little finger bend inward, the phalanx is short, and the trigeminal point of the palm shifts to the distal end. Palm prints and sandal feet are common, and about half of children with big toes are arched dermatoglyphics. It often presents drowsiness and difficulty in eating, and mental retardation becomes more and more obvious with age. IQ 25 ~ 50, delayed motor development and sexual development.

Baidu encyclopedia-xihanna foundation

Baidu Encyclopedia-Down Syndrome in Children