Genetic Mutations: Edwards syndrome

Trisomy 18 (Edwards syndrome)

Concept
It is a malformation syndrome resulting from a chromosomal imbalance. Its frequency has been estimated at 1/6000 live births and is the third most common chromosomal syndrome after the s. Down and microdeletion 22q11. It occurs in all races and geographical areas.
It is more common in older mothers: From age 35 the rate increases progressively from 1/2500 live births at age 36 to 1/500 in the 43^rd.

Etiology:
 

Trisomy of all or most of chromosome 18. 95-96% of cases are complete trisomy product nondisjunction, the remainder translocation trisomy. The partial trisomy and mosaicism for trisomy 18 often have an incomplete phenotype, absence of some of the typical anomalies s. Edwards, although in some cases the whole, typical phenotype of trisomy 18 mosaicism can be associated.

Clinical features:

• Delayed prenatal and postnatal (mean birth weight: 2,340 g) growth.
• Birth after term.
• Adipose tissue and poor muscle mass at birth.
• Initial hypotonic progressing to hypertension .
• Craniofacial microcephaly, large fontanels, prominent occiput with bifrontal narrow diameter, eye defects (corneal opacity, cataract, macroftalmia, coloboma of iris), short palpebral fissures, low-set dysplastic ears, micrognathia, small mouth, arched palate, cleft lip / cleft palate.
• Tips: trisomy hand (hand position characteristic tendency to clenched fists) hypoplastic fingernails and feet, extension limitation (> 45th) hips, prominent heel to toe short foot and dorsiflexion, hypoplasia / radial aplasia, syndactyly 2nd-3rd toes, club feet.
• Chest-abdomen hypoplastic nipples, umbilical hernia and / or groin, increased intermaxillary space, omphalocele.
• Urogenital: undescended testes, hypoplastic labia with prominent clitoris, uterine malformations, hypospadias, bifid scrotum.
• Reindeer-urologic malformations: horseshoe kidney, renal ectopic, hydronephrosis, urethral duplication, polycystic kidney.
• Cardiovascular: congenital heart disease present in 90% or more of the cases (interventricular communication with multiple valve involvement, patent ductus arteriosus, pulmonary stenosis, coarctation of the aorta, transposition of the great arteries, tetralogy of Fallot, anomalous coronary artery).
• Gastrointestinal tract: Meckel's diverticulum, ectopic pancreas, colon incomplete fixation, anterior anus, anal atresia.
• CNS: hypoplasia / aplasia of the corpus callosum, agenesis of septum pellucidum, abnormal gyri, hydrocephalus, spine bifida.
• Skin: marbled skin, hirsutism in back and front.
• Radiological signs: sternum cut with reduced ossification centers, small pelvis, and dislocated hips.

 

 

 

 

 

 Diagnosis

Demonstration in the cytogenetic study of trisomy 18.

Epidemiology

It is the second most common trisomy, just after the call Trisomy 21 Down syndrome. Its incidence is 1 / 3,000- 1 / 8,000 live births, making it highly variable depending on the population and early prenatal diagnosis. It is more common in women by a ratio of 4-1 is of maternal origin in approximately 90% of paternal origin and in only 10% of the cases (2.4) where 95% of the cases corresponds to Full trisomy and is associated with advanced maternal age. Only 50% of patients die within the first 2 months of life. The 90-95% of patients die within the first year of life, are exceptional they reached adolescence.

 

 

Edwards’s syndrome is a condition that causes multiple organ failure and that according to statistics ended in death in most cases, it is for this very reason that patients should receive palliative care, which focuses on reducing pain and suffering patients to provide the necessary measures for the relief of their symptoms. This treatment includes the work of various specialists among which pediatricians, psychologists, nutritionists, physiotherapists, occupational therapists.

Bibliography:

Antonio Perez Aytes. (2010). Trisomy 18 (Edwards syndrome). 11/13/2015, of Spanish Association of Pediatrics Website: http://www.aeped.es/sites/default/files/documentos/trisomia_18.pdf