What are the Characteristics of Trisomy 21 children?

Although not all Down syndrome infants share the same distinguishing physical characteristics, some may have traits to a larger or lesser degree. A preliminary diagnosis can usually be made at birth just by looking at the baby. If the attending physician suspects Down syndrome, a karyotype - a blood or tissue sample stained to show chromosomes grouped by size, number, and shape - will be performed to verify the diagnosis.

The most familiar physical traits of Down syndrome include:

Low muscle tone (muscle hypotonia)

Flat facial profile, including a somewhat depressed nasal bridge and small nose

Upward slant to the eyes (oblique palpebral fissures)

Abnormal shape and small size of the ears (dysplastic ears)

Single deep crease across the center of the palm (simian crease)

Excessive ability to extend the joints (joint hypermobility)

Fifth finger has one bending joint instead of two (dysplastic middle phalanx)

Small skin folds on the inner corners of the eyes (epicanthic folds)

Excessive space between large and second toe (sandal gap)

Enlargement of tongue in relationship to size of mouth


Children with Down syndrome can exhibit these traits in varying degrees. In addition to the characteristics above, half of the children born with Down syndrome have congenital heart defects. The majority of these defects can be corrected, resulting in long-term health improvements. Children with Down syndrome also tend to have increased susceptibility to infection, respiratory problems, eye problems, thyroid dysfunctions, obstructed digestive tracts (early in infancy), and childhood leukemia. Recent medical advances have made most of these health problems treatable, however, and people born with Down syndrome now have an average life expectancy of 55 years.

While children with Down syndrome continue to acquire physical and mental skills throughout their lives, their ability levels vary considerably. In general, their average rate of progress will be slower than ordinary children. Because speech may also be delayed, careful attention should be paid to a child's hearing. Retention of fluid in the inner ear is a common cause of hearing and speech problems.