1 and 2 1 trisomy syndrome, also known as congenital stupidity or down syndrome, is an autosomal aberration and the most common chromosomal disease in children. 2 1 trisomy syndrome contains a series of genetic diseases, among which the most representative chromosome 2 1 trisomy phenomenon will lead to high deformity including learning disabilities, mental retardation and disability. Its clinical features are as follows:
(1) In body shape: short stature, low muscle tension, low physical strength and fragile cervical spine. The head length is shorter than that of ordinary people, the facial undulation is smaller, and the eyelid fissure can be slightly tilted upward and outward, forming a face similar to that of Mongols. The part between the nose and eyes is low, the corner of the eye is picked up, and the eyelids are deep. Hair is soft and less. The upper part of the ear bends inward and looks round and low as a whole. The tongue is bigger. A strong neck. The hands are wide, the fingers are short, the thumb and forefinger are far apart, and the little finger lacks joints and bends inward. There is only one horizontal stripe on the palm, and the fingerprint is arched. The two horizontal stripes on the palm are combined into one, which is called "ape stripe", also known as "crossing the hand". The interval between the first toe and the second toe is also relatively large. Limbs are short, and joints can be excessively bent due to ligament relaxation. Bone age often lags behind age, delayed teething and frequent dislocation. Not all of the following characteristics appear in patients. According to individual differences, there are also examples where physical characteristics are not obvious.
(2) In terms of intelligence and development, it is mainly manifested as mental retardation, physical retardation and special face. Children with wide eye distance, flat nose, small eye fissure, oblique lateral eye, inner edge epidermis, small external ear, narrow hard palate, tongue often sticking out of the mouth and drooling, so it is called tongue-like dementia. Children have obvious special faces when they are born, and often show problems and feeding difficulties. With the increase of age, mental retardation is gradually obvious, and motor development and sexual development are delayed. About 30% of children are accompanied by congenital heart disease and other malformations. Because of low immune function, it is easy to suffer from various infections, and the incidence of leukemia is also increased by 10 ~ 30 times. Gastrointestinal abnormalities such as duodenal stenosis, atlantoaxial joint instability and strenuous exercise can lead to spinal cord compression. Alzheimer's disease is almost common in patients in their forties. It is characterized by inattention, reticence, poor visual and spatial orientation, decreased memory and judgment, and seizures. If you live to adulthood, you will often have symptoms of Alzheimer's disease after 30 years old.
2. The incidence of neonatal 13 trisomy syndrome (Patau syndrome) is about1:25,000, which is significantly higher in women than in men, and multiple malformations in children are more serious than 18 trisomy syndrome and 2 1 trisomy syndrome.
The clinical manifestations of trisomy 13 syndrome are as follows: (1) From the appearance and body shape, the child has a small head, a backward forehead, a narrow temporal region, a wide anterior fontanel and bony suture, and an ulcer on the scalp at the top of the skull. At the level of blepharoptosis, there are different degrees of small eyes to no eyes, wide eye distance, cataract, iris defect and abnormal retinal development. One eye, large flat triangular mouth, thin mouth and small jaw can be seen. 2/3 cases showed upper cleft lip, often bilateral, accompanied by cleft palate. Low ear position, flat helix and unclear boundary, deafness. There may be one or more hemangiomas on the face, forehead or behind the neck. The neck skin is slack. Finger flexion overlap or with or without, common six fingers (toes), excessive nail protrusion. Feet like the bottom of a rocking chair, heels protruding.
(2) Growth and intellectual development: growth and development disorders, difficulty in eating, poor vitality, mental retardation, low muscle tone, sudden fear symptoms, apnea and exercise convulsions, accompanied by irregular changes in EEG peak rhythm. 80% cases have congenital heart disease, mainly ventricular septal defect, patent ductus arteriosus, atrial septal defect and so on. Gastrointestinal malformations can be seen as malrotation of colon, umbilical hernia and inguinal hernia, heterotopic pancreas or spleen tissue, etc. 30 ~ 60% children have urinary system malformations, including polycystic kidney, hydronephrosis, double kidneys and double ureters. 80% of men have cryptorchidism, accompanied by scrotum malformation, and women may have double horns uterus, clitoral hypertrophy and double vaginas.
3. Trisomy 18 syndrome refers to an extra chromosome after chromosome examination, which is considered as chromosome 17. Many scholars have reported similar observation results, confirming that these clinical syndromes are related to the abnormality of chromosome 18. The incidence of live infants is 1/4000, which is more common in women. The average childbearing age of the patient's mother is 34 years old.
The clinical manifestations of (1) are: growth retardation, ptosis, eyelid deformity, low ear position, small mouth, small chin, skin spots, finger clenching beyond the middle finger, finger (toe) deformity, toe-lifting, large and short toes, ventricular septal defect, umbilical hernia, etc.
4. Meow syndrome: Criduchat syndrome, also known as cri-du-chat syndrome, Bitang's syndrome is more common, which is caused by the short arm deletion of chromosome 5.
The symptoms of (1) are as follows: a baby will cry like a kitten from a few weeks to several months after birth, with low intellectual development in childhood and low muscle tone, which will turn into high muscle tone in adulthood; The distance between eyes is too wide, short head deformity, full moon face, downward inclination of the outer corner of the eye, anti-congenital stupid blepharoptosis, micrognathia, low tension and strabismus. Most of these characteristics are obvious in childhood and may disappear with age.
(2) When vocalizing, the crying is small, the weight is light, the head is small, the face is small, the larynx is small, and the epicanthus is overgrown. The most prominent thing is that the newborn cries like a cat, with mental retardation, strabismus, wide eye distance, congenital heart disease, high palatal arch, abnormal palmprint and long fingers and toes.
5. Fragile X syndrome is caused by mutation during the formation of human X chromosome. This syndrome is the most common cause of hereditary mental retardation. Because women have two X chromosomes, the involvement rate is 50%, and the degree is relatively light. It is estimated that more than 10% of male children with hereditary mental retardation have abnormal fragile X chromosome, and sometimes women will be involved, but the condition is mild.
(1) The child shows a typical triad: mental retardation, special appearance (such as long face, big ears, wide forehead, big and wide nose and high palatal arch), and large testicles. The child's height is normal, and the big testicles usually appear at the age of 8-9. 85% of children may have mental retardation, mostly moderate, often manifested as abnormal behavior, mostly self-destructive behavior, hyperactivity and impulsive behavior before puberty, as well as stiff and weird movements, hyperactivity and talkativeness. Autistic people may have unique clapping movements. 9% ~ 45% children can have seizures.
6. A circular chromosome refers to a bivalent chromosome whose centromere is located near the midpoint and its two ends cross during the late to middle stage of the first meiosis. It is characterized by mental retardation and various physical deformities.
7. Creutzfeldt-Jakob syndrome: Its chromosome phenotype is XXY, which is only found in men.
(1) Clinical manifestations: The patient is tall, similar in appearance to those without testicles, with shoulder width, sparse hair and body hair, high tone, feminization of breasts and testicles, decreased muscle tone, usually accompanied by mental retardation, but to a lesser extent. The disease is complicated with psychosis, asthma and endocrine dysfunction, such as diabetes.
8. Turner syndrome: The chromosome is XO(45X) type, which is only found in women.
(1) Clinical manifestations: The patient is short in stature, with webbed neck, triangular face, small chin, wide nipple spacing, finger (toe) flexion, elbow valgus, nail hypoplasia, and may be accompanied by facial features, epicanthus, sexual retardation and moderate mental retardation.
9. Vaginal head syndrome is a rare brain malformation with many causes, some of which are caused by chromosome 8 triploid chimera, and it is often misdiagnosed as various types of ventricular dilatation with abnormal brain development. The patients showed mental retardation, spasms and seizures, as well as visual abnormalities caused by optic nerve hypoplasia. The occipital angle of lateral ventricle is obviously enlarged, the edge of cortical gray matter overlaps and thickens, and the white matter becomes thinner.
10, Williams syndrome: Williams syndrome is a slight deletion of the gene region encoding elastin on chromosome 7, and the incidence of newborns is 1/20000, which was first described by Williams.
(1) Clinical manifestations: The patient has mental retardation, precocious musical ability, extraordinary musical ability and amazing memory of music scores. After listening to the symphonies, he can remember them all. Some patients can write long descriptions with correct wording and content, but they cannot describe simple things. Children with developmental retardation have a unique appearance, such as a big mouth, almond eyes, upturned nostrils and small pointed ears, which is called "leprechaun-like" appearance; Mild personality, sensitive to auditory stimuli, late acquisition of verbal communication ability, defective visual space and motor ability. There may be cardiovascular malformations such as aortic stenosis.
The incidence rate of newborns with 1 1 and Prader-Willi syndrome is1/20,000, and the prevalence rate of males and females is similar, which is caused by the deletion of chromosome q 1 1-q 13 of 15.
(1) Clinical manifestations: The child showed decreased muscle tone, disappearance of tendon reflex, short stature, facial deformity, obvious obstruction of genital development, and flexion of joints at birth. 1 year later, they have obvious mental retardation or mental retardation, and they are obese because of overeating.
12 and Angelman syndrome are caused by the deletion of chromosome q 1 1-q 13 of 15. Unlike Prader-Willi syndrome, the disease is caused by a single genetic defect in the mother.
(1) Clinical manifestations: The child showed severe mental retardation, microcephaly and early seizures, was insensitive to antiepileptic drugs, had rare puppet-like posture and dyskinesia, and often wanted to laugh or smile, which was formerly called "Happy Puppet Syndrome".
Rett syndrome: Rett syndrome was first described by Rett (1966), with unknown etiology and dominant inheritance of X chromosome. Some people speculate that metabolic mechanism is involved in the pathogenesis. The incidence rate is115000 ~110000, which is only found in women and can survive for many years. Men are homozygous and often cannot survive. If it is a female, she develops normally at birth and early after birth, and loses voluntary movement of her hand in 6 ~ 15 months, and then loses her communication ability, stunted physical development and enlarged skull.
The typical symptoms of (1) are hand peristalsis, stiff movement of rubbing pills, gradual ataxia and rigidity of lower limbs, and finally loss of walking and language ability. Paroxysmal hyperventilation and breath holding, normal breathing rhythm at night and seizures may occur.
(2) Note that this disease can be misdiagnosed as Canner's Loneliness Syndrome. The difference between them is that Wright's syndrome loses motor ability in the early stage, and there is no inattention and joint eye movement disappears. Mainly according to the child's characteristic symptoms, signs and chromosome examination. Can diagnose chromosomal abnormalities.