What is Edwards syndrome?

Edwards syndrome is a very common chromosomal trisomy. The most common symptom of this disease is that the child will have severe deformities. Many of these children die during labor or immediately after delivery. Regular prenatal check-ups during pregnancy are very important and critical for a family. High-risk pregnant women have a high chance of developing 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

syndrome) is the second most common chromosomal trisomy after idiocy. In 1960, Edwards et al. first reported a child with multiple malformations. Chromosome examination revealed an extra chromosome, which was believed to be chromosome 17. Subsequently, many scholars reported similar observations, confirming that these clinical syndromes were related to abnormalities of chromosome 18.

Edwards syndrome causes

The vast majority of cases are trisomy of chromosome 18 in all cells, and a few are partial trisomy of chromosome 18 caused by mosaicism and chromosome breakage and translocation. Trisomy is mostly from older mothers, with the average maternal age at birth being 32 years old. Translocations can arise from new mutations (denovo) or be inherited from the parents of balanced translocation carriers. The translocation type may only cause partial trisomy of the short arm, centromere, and long arm of chromosome 18.

Clinical manifestations

1. Growth and development disorders Newborns are often born post-term, with an average gestational age of 42 weeks. Children with this disorder are generally born with a low birth weight, often with a small placenta, and most have a unilateral umbilical artery. Patients have delayed mental and motor development, small stature, difficulty breastfeeding, weak response to sound, and poor bone and muscle development.

2. Multiple deformities

(1) Craniofacial area: The head has a long anteroposterior diameter and a small head circumference, and the occipital bone is prominent. The distance between the eyes and eyebrows is widened, and there are epicanthus on both sides. Corneal opacity, ectropion, and microphthalmia are common. The nose bridge is slender and raised. The nostrils are often turned up, the mouth is small, the palate is high and narrow, and the mandible is small. The ears are low, the ears are flat and the upper part is pointed. In addition, there are occasional deformities such as meningocele, cleft lip and palate, choanae atresia, and external auditory canal atresia.

(2) Chest: Short neck, webbed neck. Short sternum, small nipples, poor development, and far distance between the two nipples. More than 95% of cases have heart malformations, the most common of which are ventricular septal defect and patent ductus arteriosus, while atrial septal defect is rare. Other abnormalities include bivalvular aorta or pulmonary artery, coarctation of the aorta, tetralogy of Fallot, aorta overlying dextrocardia, right aortic arch, etc. These cardiovascular malformations are often the cause of death. Esophageal tracheal fistula and abnormal lobulation or absence of the right lung may also occur.

(3) Abdominal movement: Abdominal muscle defects are often caused by umbilical hernia and inguinal hernia. Pyloric stenosis and diaphragmatic hernia are also common. Other symptoms include ectopic pancreas or spleen, malrotation of the intestine, and hypoplastic gallbladder. Renal malformations include polycystic kidney, ectopic kidney, horseshoe kidney, hydronephrosis, megaureter and double ureter. Pelvic stenosis is relatively common in health searches.

(4) Limbs: The hand posture is a characteristic manifestation of Edwards syndrome: the fingers are flexed, the thumb, middle finger and index finger are tightly closed, the index finger is pressed on the middle finger, the little finger is pressed on the ring finger, the fingers are not easy to straighten, the nails are poorly developed, and the index and middle fingers often have syndactyly and polydactyly. The fifth metacarpal is short, the big toe is short and dorsiflexed, and the thigh abduction is limited due to increased muscle tension. Congenital hip dislocation and occasional short limb deformity are present.

(5) Genital cupping: One-third of boys have hidden testicles, and one-tenth of girls have poor development of the clitoris and labia majora. Perineum abnormalities and anal atresia are often seen. Rare cases include ovarian hypoplasia, bicornuate uterus, and scrotal fission.

(6) Endocrine system: There may be thyroid hypoplasia, thymus and adrenal gland hypoplasia.

(7) Skin: The skin has many vellus hairs and wrinkles. Fingerprint features include more than 6 arch patterns, only one horizontal pattern on the fifth finger, and 30% have a through-hand (or ape line).

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