Down’s syndrome

Down’s syndrome

    The classic phenotype of Down syndrome include a flattened occiput, midfacial hypoplasia, depressed nasal bridge, upward Slanting palpebral fissures, epicanthic folds , grayish speckling of the iris (Brushfield spots). Micrognathia excess nuchal skin, single palmer creases(simian creases), single flexion creases and incurving of the fifth fingers (clinodactyly) and increased distance between the first and second toes. Down syndrome may present with marked hypotonia ;congenital heart defects, duodenal atresia and tracheoesophageal fistula. However it is imperative that cytogenetic studies be done to confirm the diagnosis and to differentiate a nondisjunctional triosomy from translocation .In case of translocation Down syndrome karyotyping  is indicated for parents to detect balanced translocation carrier  

Recurrence  risk of Down syndrome

    The risk increases sharply when the mothers age is above 35 years for the non disjunction group (age-dependent) ,

 affected females who become pregnant have a high risk (30–50%) of having a Down syndrome child .

The translocation group is usually age independent specially if it is familial translocation.

However ,the recurrence risk of Down syndrome is high if the mother is a translocation carrier, such a condition there is one in three risk of having an effected child at any one pregnancy .