Trisomy E syndrome

Trisomy E syndrome, also known as Trisomy 18 or Edwards syndrome, is a genetic disorder caused by the presence of an extra 18th chromosome. This condition is characterized by a combination of birth defects including developmental delays, growth deficiency, and distinctive facial features. It is the second most common autosomal trisomy, after Down syndrome, that carries to term.

Causes and Diagnosis

Trisomy 18 is caused by a chromosomal anomaly in which a person has three copies of chromosome 18 instead of the usual two. This can occur due to nondisjunction during meiosis, the process by which gametes (sperm and egg) are formed. The extra chromosome can come from either the mother or the father, but maternal age is a known risk factor.

Diagnosis of Trisomy 18 can be made prenatally through screening tests such as the first trimester combined test, which includes a blood test and an ultrasound. Further diagnostic testing can include chorionic villus sampling (CVS) or amniocentesis, which involve analyzing chromosomes in fetal cells.

Symptoms and Features

Infants with Trisomy 18 often have a low birth weight, heart defects, and a small, abnormally shaped head. Other common physical features include a small jaw, clenched fists with overlapping fingers, and underdeveloped thumbs. Due to the severity of health problems, many infants with Trisomy 18 do not survive beyond their first year of life. However, with supportive care, some children can live into their teens and beyond.

Management and Treatment

There is no cure for Trisomy 18, and treatment focuses on managing symptoms and improving quality of life. This may involve surgeries to correct physical anomalies, therapies to address developmental delays, and palliative care. Decisions about the extent of medical intervention are highly personal and vary greatly among families and healthcare providers.

Prognosis

The prognosis for individuals with Trisomy 18 is generally poor, with a high rate of neonatal and infant mortality. However, every individual is unique, and some children with Trisomy 18 defy the odds and live beyond infancy. The quality of life for these children can vary widely depending on the severity of their symptoms and the medical and supportive care they receive.

Ethical Considerations

The diagnosis of Trisomy 18 raises complex ethical issues, particularly regarding prenatal testing and the extent of medical interventions for infants with severe disabilities. These decisions are deeply personal and involve considerations of quality of life, medical capabilities, and family values.

See Also

• Genetic disorder
• Chromosomal abnormalities
• Prenatal diagnosis
• Palliative care

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