Early Infantile Overgrowth due to XYY Syndrome

Abstract

Abstract. A 20-months-old boy was referred for evaluation of his growth and development . Past history revealed that he was the first offspring of a healthy mother at full term and by normal delivery (3,600 g in weight and 52 cm in length). His early milestones were normal, but overgrowth was already noted in early infancy. He weighed 9.5 kg and was 68 cm tall at four months of age. On physical examination at 20 months, he weighed 17 kg (+4.22 SD) and was 88.4 cm tall (+2.05 SD) with a head circumference of 51.4 cm (>2 SD). He was somewhat hyperactive, but did not have temper tantrums or show aggressive behavior. His psychomotor development was delayed with a DQ of 62. EEG showed abnormal basic activity. Chromosome analysis revealed XYY mosaicism. The case demonstrated overgrowth of early infantile onset due to XYY syndrome.