CdLS is a congenital syndrome, meaning it is present from birth. Most of the signs and symptoms may be recognized at birth or shortly thereafter. A child need not demonstrate each and every sign or symptom for the diagnosis to be made. A gene on chromosome 5 was discovered in 2004 to be involved in CdLS in 50% of cases. Genetic research since has revealed two other chromosome sites connected with the syndrome. See Medical Page for more detailed information.

As with some other syndromes, individuals with CdLS strongly resemble one another. Common characteristics include: low birth weight (usually, but not always, under five pounds), delayed growth and small stature, and small head size (microcephaly). Typical facial features include thin eyebrows which frequently meet at midline (synophrys), long eyelashes, short upturned nose and thin, downturned lips.

Other frequent findings include excessive body hair (hirsutism), small hands and feet, partial joining of the second and third toes, incurved fifth fingers, gastroesophageal reflux, seizures, heart defects, cleft palate, bowel abnormalities, feeding difficulties, and developmental delay. Limb differences, including missing limbs or portions of limbs, usually fingers, hands or forearms, are also found in some individuals.