We present a mildly affected girl with de novo dup(17)(p11.2p11.2). The patient was evaluated because of minor anomalies noted during a hospitalization for nonrecurrent tonic-clonic seizures associated with transient hypoglycemia. She also had unilateral renal hypoplasia and relative short stature, but at 2 years of age, she scored within the low normal range on neurodevelopmental examinations. Compared with other similar duplications, this patient represents the milder range of the spectrum for this karyotypic abnormality. Am. J. Med. Genet. 94:296-299, 2000.