Some young children with Williams syndrome have elevations in their blood calcium level. The true frequency and cause of this problem is unknown. Occasionally, dietary or medical treatment is needed. In most cases, the problem resolves on its own during childhood, but lifelong abnormality in calcium or Vitamin D metabolism may exist and should be monitored. Most children with Williams syndrome have a slightly lower birth-weight than their brothers or sisters.
Adult stature is slightly smaller than average.
Feeding problems Many infants and young children have feeding problems. Feeding difficulties tend to resolve as the children get older. Many infants with Williams syndrome have an extended period of colic or irritability. This typically lasts from 4 to 10 months of age, then resolves. It is sometimes attributed to hypercalcemia.