Trisomy 18 Facts

Trisomy 18 is a genetic disorder in which a person has a third copy of material from chromosome 18, instead of the usual two copies where the extra material affects the normal development.

Trisomy 18 is three times more common in girls than boys.

Symptoms

·         Clenched hands

·         Crossed legs

·         Feet with a rounded bottom (rocker-bottom feet)

·         Low birth weight

·         Low-set ears

·         Mental delay

·         Poorly developed fingernails

·         Small head (microcephaly)

·         Small jaw (micrognathia)

·         Undescended testicle

·         Unusual shaped chest (pectus carinatum)

Exams and Tests

An exam during pregnancy may show signs that the child will have Trisomy 18. It may  show an unusually large uterus and extra amniotic fluid and there may be an unusually small placenta when the baby is born.

signs include:

·         Hole, split, or cleft in the iris of the eye (coloboma)

·         Separation between the left and right side of the abdominal muscle (diastasis recti)

·         Umbilical hernia or inguinal hernia

There are often signs of congenital heart disease, such as:

·         Atrial septal defect (ASD)

·         Patent ductus arteriosus (PDA)

·         Ventricular septal defect (VSD)

Tests may also show kidney problems, including:

·      Horseshoe kidney

·         Hydronephrosis

·         Polycystic kidney