Williams syndrome is characterized by a wide spectrum of symptoms and physical features that vary greatly in range and severity, even among affected family members. Individuals with Williams syndrome will not have all the symptoms listed below. Some affected individuals do not have heart (cardiac) abnormalities; others may not have elevated levels of calcium in the body (hypercalcemia). In addition, the severity of these symptoms often varies greatly from case to case.
Some children with Williams syndrome may have a low birth weight, feed poorly, and fail to gain weight and grow at the expected rate (Failure to thrive). Symptoms such as Vomiting, gagging, diarrhea, and constipation are common during infancy. Some affected infants may have elevated levels of calcium in their blood (hypercalcemia), leading to loss of appetite, Irritability, Confusion, Weakness, easy fatigability, and/or abdominal and muscle pain. Calcium levels usually return to normal around the age of 12 months. However, in some cases, hypercalcemia may last into adulthood. Linear growth may be delayed during the first four years of life. However, growth spurts usually occur between the age of five and 10 years. Most people with Williams syndrome are less than average height during their adult years.
Newborns with Williams syndrome have characteristic “elfin-like” facial features including an unusually small head (microcephaly), full cheeks, an abnormally broad forehead, puffiness around the eyes and lips, a depressed nasal bridge, broad nose, and/or an unusually wide and prominent open mouth. Additional features may include a vertical skin fold on the inner corners of the eyes (epicanthal folds), a small pointed chin, prominent ears, and/or an unusually long vertical groove in the center of the upper lip (philtrum). Some infants with Williams Syndrome may have dental abnormalities including malformed teeth (i.e., hypoplastic enamel), small teeth (microdontia), and upper and lower teeth that do not meet properly (malocclusion).
A star-like (stellate) pattern in the iris of the eye may be apparent in about 50 percent of children with this disorder. It is most pronounced in those infants with blue or green eyes. This pattern may be harder to see in those children with darker eyes or it may not be present. Affected infants may also experience inward deviation of the eyes (esotropia) and farsightedness (hyperopia).
Children with Williams syndrome are extremely sensitive to sound and may overreact to unusually loud or high-pitched sounds (hyperacusis). Chronic middle ear infections (otitis media) are often present.
Motor development, (e.g., sitting and walking) and/or gross and fine motor skills (e.g., picking up an object) may be delayed. The development of secondary sexual characteristics (e.g., pubic hair and underarm hair) may occur prematurely (precocious puberty) in children with this disorder. Breast development and menstruation may occur earlier than expected in females with Williams syndrome. Individuals with this disorder may also have an unusually hoarse voice.
Congenital heart defects (CHD) occur in approximately 75 percent of children with Williams syndrome. The most frequent defect is supravalvar aortic stenosis, a condition characterized by the narrowing of the aorta above the aortic valve. The aorta is the main artery of the vascular system. Blood passes from the left ventricle of the heart, through the aortic valve, and into the aorta. In supravalvar aortic stenosis, the area above the aortic valve becomes unusually narrow. Symptoms may include Fatigue, pain in the chest, Dizziness, unusual heart sounds (murmurs) and/or temporary loss of consciousness (syncope). The amount of narrowing of the aorta may vary among affected individuals.
Additional congenital heart defects associated with Williams syndrome may include pulmonary artery stenosis, and/or septal defects. (For more information on these heart defects, see the Related Disorders section of this report.) Abnormally high blood pressure (hypertension) is also common in adults with this disorder.
Children with Williams syndrome typically have a personality that is friendly, outgoing, and/or talkative. The appropriate use of language and vocabulary range may be unusually enhanced in some children with this disorder. Mild to moderate mental retardation may occur. However, some children are of average intelligence with severe learning disabilities. Hyperactivity and attention deficit disorder are also common, although most affected individuals have good long-term memory. Some affected individuals may have visual difficulties; they may tend to view a picture in parts as opposed to seeing it as a whole.
Older children and adults with Williams syndrome may develop progressive joint problems that limit their range of motion. Skeletal abnormalities such as backward (lordosis), front-to-back (kyphosis), and side-to-side (scoliosis) curvature of the spine may also be present. Some affected individuals may have a sunken breastbone (pectus excavatum) and inward turning of the great toe toward the other toes (hallux valgus). Skeletal and joint abnormalities may result in an abnormal manner of walking (awkward gait). Skeletal abnormalities may become worse as affected individuals age.
Additional abnormalities may occur in some individuals with Williams syndrome including kidney (renal) abnormalities, chronic urinary tract infections, an underdeveloped (hypoplastic) thyroid gland, and umbilical or inguinal hernias.