Edwards syndrome
Overview
Edwards' syndrome is caused by an extra copy of chromosome 18. For this reason, it is also called trisomy 18 syndrome. The extra chromosome is lethal for most babies born with this condition. It causes major physical abnormalities and severe mental retardation, and very few children afflicted with this disease survive beyond a year.
Symptoms
- Mental retardation
- Prominent occiput
- Micrognathia
- Low set ears
- Rocker bottom feet
- Flexion deformities on the fingers
- Congenital heart disease
- Congenital heart disease
- Low birth weight
- Weak infants
- Poor feeding in infants
- Weak crying in infants
- Failure to thrive
- Small lower jaw
- Recessed chin
- Prominent back of skull
- Extreme rigidity
- Overlapping fingers
- Hypoplastic nails
- "rocker bottom" feet
- Low set malformed ears
- Mental retardation
- Short sternum
- Small pelvis
- Single umbilical artery
- Profound retardation
- Small narrow cranium
- Prominent back of skull
- Posteriorly rotated ears
- Small mouth
- Pulmonic stenosis
- Aortic narrowing
- Ventricular septal defect
- Auricular septal defect
- Patent ductus arteriosus
- Cleft palate
- Clubfoot deformity
- Renal malformation
- Brain anomalies
- Choanal atresia
- Eye malformation
- Vertebral anomalies
- Hypospadias
- Limb defects
Causes
Most cases of trisomy 18 syndrome are caused by spontaneous meiotic nondisjunction. The risk of chromosomal abnormalities typically increases with maternal age; however, the mean maternal age for this disorder is 32½. Incidence is 1 in 3,000 neonates, with females three times more likely to be affected than males.
Diagnosis
Physical abnormalities point to Edwards' syndrome, but definitive diagnosis relies on karyotyping. Karyotyping involves drawing the baby's blood or bone marrow for a microscopic examination of the chromosomes. Using special stains and microscopy, individual chromosomes are identified, and the presence of an extra chromosome 18 is revealed. Trisomy 18 can be detected before birth. If a pregnant woman is older than 35, has a family history of genetic abnormalities, has previously conceived a child with a genetic abnormality, or has suffered earlier miscarriages, she may undergo tests to determine whether her child carries genetic abnormalities. Potential tests include maternal serum analysis or screening, ultrasonography, amniocentesis, and chorionic villus sampling.
Prognosis
Most children born with trisomy 18 die within their first year of life. The average lifespan is less than two months for 50% of the children, and 90-95% die before their first birthday. The 5-10% of children who survive their first year are severely mentally retarded. They need support to walk, and learning is limited. Verbal communication is also limited, but they can learn to recognize and interact with others.
Treatment
There is no cure for Edward's syndrome. Since trisomy 18 babies frequently have major physical abnormalities, doctors and parents face difficult choices regarding treatment. Abnormalities can be treated to a certain degree with surgery, but extreme invasive procedures may not be in the best interests of an infant whose lifespan is measured in days or weeks. Medical therapy often consists of supportive care with the goal of making the infant comfortable, rather than prolonging life.