Head circumference of children with Williams-Beuren syndrome.

Head circumference is considered an important parameter of brain growth and development. Syndrome-specific standards for head circumference in Williams-Beuren syndrome (WBS) are not available to date, although mental retardation is a leading manifestation in the syndrome. Therefore, we investigated head growth in 63 girls (251 measurements) and 88 boys (298 measurements) with WBS between birth and adulthood. Most measurements in both sexes were from the first 4 years of life (n = 162 in girls and n = 189 in boys). Mean (+/- SD) head circumference at birth was 33.39 +/- 1.38 cm and 34.02 +/- 1.44 cm for term girls and boys, respectively. Although head growth in WBS girls and boys was at a slower velocity, the pattern of head circumference was similar to that in the normal population. After the age of 3 months, head circumference started to fall below the normal mean in girls (0.5-2 cm). In boys, mean head circumference was below the normal mean already at 1 month of age (2 cm). The deficit increased to 3 cm from 6 months to 4 years. Adult OFC was 52.85 +/- 1.75 cm (n = 16) compared to 55.70 +/- 1.83 cm (n = 46; P < 0.00001) in WBS women and 55.51 +/- 1.68 cm (n = 30) compared to 57.87 +/- 1.29 cm (n = 31; P < 0.00001) in WBS men. During development, microcephaly is only seen in about one third of WBS patients.