Trisomy 18 risk

Opportunities and risks coexist in investment, and those who dare to take risks often get considerable rewards. Unlike investing, we don't put our bodies at risk. If we knew a disease was going to occur, we would all try to stop it in its early stages. Trisomy 18 is something that pregnant women will encounter during prenatal checkups. I believe that many pregnant mothers will encounter this when checking their babies for deformities. So what is the risk factor for trisomy 18?

The screening for trisomy 18 mainly depends on the test value of alpha-fetoprotein, which should be greater than the reference value. The lower the test value, the higher the chance of the fetus suffering from Down syndrome. The higher the chorionic gonadotropin, the higher the chance of the fetus suffering from Down syndrome. The alpha-fetoprotein value, chorionic gonadotropin value, and the age, weight, and gestational age of the pregnant woman are entered into the computer, and the computer calculates the risk of the fetus developing Down syndrome. If the test results show that the risk is lower than 1/270, it means that the risk is relatively low, and the chance of the fetus developing trisomy 18 is less than 1%. If the risk is higher than 1/270, it means that the fetus is at high risk of disease, and further amniocentesis or chorionic villus sampling should be performed to ensure whether the fetus is deformed. It is recommended to keep emotions stable, pay attention to rest, strengthen nutrition and do some appropriate exercise.

Trisomy 18 is also known as Edwards syndrome. The malformations of trisomy 18 mainly include abnormalities of the mesoderm and its derivatives (such as bones, urogenital system, and heart, which are the most obvious). In addition, the ectoderm (such as skin folds, skin ridges and hair) and endoderm (such as Meckel's diverticulum, lungs and kidneys) close to the mesoderm are also abnormal. Literature reports that the embryo develops normally before 5 weeks of pregnancy, and abnormalities begin to appear between the 6th and 8th weeks of pregnancy.

18-trisomy syndrome (Edwards

Trisomy 21 syndrome is the second most common autosomal trisomy after trisomy 21. First reported by Edwards et al. in 1960. The main clinical manifestations are multiple malformations and severe mental retardation. The incidence of this disease in newborns is 1:4000 to 1:5000, and the male to female ratio is 1:3 to 1:4. There is a tendency for concentrated occurrence in a certain period or region. Trisomy 18 is also known as Edwards syndrome.

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Symptoms/Trisomy 18

1. Growth and development disorders

Growth disorders before and after birth, mostly small for gestational age (average about 2240g), symptoms of trisomy 18 syndrome are feeding difficulties, poor response, and poor bone and muscle development. Neonatal muscle tone is low in the early stage and increases later, thus limiting the ability of the thigh to fully abduct. Mental and motor developmental delays.

2. Multiple deformities

(1) Craniofacial: Microcephaly. The head has a long anteroposterior diameter and a prominent occipital bone; microphthalmia, wide eye distance, epicanthus, corneal opacity, cataract, iris defect, etc.; choanae atresia; high and narrow palate, small mandible, cleft lip or palate; low-set ears and deformed ears.

(2) Chest: short neck, short sternum, small and underdeveloped nipples, wide distance between breasts, and underdeveloped or absent 12th rib.

(3) Various congenital malformations: 80% to 95% of cases have congenital heart disease. The manifestations of trisomy 18 syndrome are mainly ventricular septal defect, patent ductus arteriosus, atrial septal defect, etc. Digestive tract malformations may include colon malrotation, umbilical and inguinal hernia, pyloric stenosis, Meckel’s diverticulum, etc. 30% to 60% of children have urinary tract malformations, including polycystic kidney, ectopic kidney, horseshoe kidney, hydronephrosis, double kidney and double ureter, especially horseshoe kidney, duplicated kidney and double ureter. Males often have cryptorchid testes and scrotal deformities; females may have a bicornuate uterus, clitoral hypertrophy, and double vagina. There may be thyroid hypoplasia and thymus hypoplasia.

(4) Limbs: Children with trisomy 18 have a special fist-making posture: the fingers are flexed, the thumb, middle finger and index finger are tightly closed, the index finger is pressed on the middle finger, and the little finger is pressed on the ring finger. The fingers are not easy to straighten. If they are passively straightened, the middle finger and little finger are tilted to the ulnar side, the thumb and index finger are tilted to the radial side, and the index finger and middle finger are separated to form a "V" shape. Nail hypoplasia. The big toe is short and dorsiflexed, with prominent bones, giving the foot a rocking-chair-bottom appearance. Short limb deformity is occasionally seen.

(5) Skin and skin texture: The skin is hairy, wrinkled, and has hemangiomas. Fingerprint features include more than six arched lines, only one horizontal line on the fifth finger, 30% have a through-hand (or ape line) and the axial triradiate is distal, in the shape of t' or t".

3. Severe intellectual disability.

4. X-ray examination shows that trisomy 18 is manifested by short thumbs and first metacarpal bones, ulnar deviation of the 3rd, 4th and 5th fingers, thin skull vault, prominent occipital bone, hypoplastic maxillary and mandibular bones, hypoplastic or absent inner third of clavicle, thin and pointed ribs, hypoplastic sternum, reduced ossification centers and abnormal segmentation of the sternum.