Down's Syndrome (Trisomy 21) can often be suspected based on phenotypic features.


Head and Face:

(1) brachycephaly and microcephaly, with flat occiput

(2) epicanthal folds with upward slanting palpebral fissures

(3) flat nasal bridge

(4) small and/or open mouth, with protruding tongue

(5) Brushfield spots on the iris

(6) ears may be small, cupped and/or show a folded-over upper helix

(7) small ear canals

(8) redundant nuchal skin in the neonate


Sensory and cognitive disorders

(1) congenital lens opacities, cataracts, glaucoma or other ocular disorders

(2) hearing loss

(3) mental retardation


Internal viscera:

(1) cardiac malformations

(2) duodenal or other gastrointestinal atresia



(1) brachydactyly

(2) broad hands with single palmar crease

(3) deformed middle phalanx of the fifth finger, with single crease or clinodactyly (lateral or medial bending)

(4) wide gap between first and second toes

(5) lax ligaments (hyperextensible joints)

(6) hypotonia

(7) short stature

(8) short humerus and femur

(9) acquired hip dislocation



• The phenotypic features may vary with racial groups. In addition, the features may be hard to recognize in an unfamiliar ethnic group. Thus, phenotypic features can help identify patients who require additional evaluation, but karyotype analysis is required for definitive diagnosis.

• Some phenotypic features may be difficult to identify in premature infants,


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